Load Transducer and Force Measurement Assembly Using the Same

ABSTRACT

A load transducer is disclosed herein. The load transducer includes a plurality of beam portions connected to one another in succession, the plurality of beam portions being arranged in a circumscribing pattern whereby a central one of the plurality of beam portions is at least partially circumscribed by one or more outer ones of the plurality of beam portions; and at least one load cell disposed on one of the plurality of beam portions, the at least one load cell configured to measure at least one force or moment component of a load applied to the load transducer. A force measurement assembly including a plurality of load transducers with beam portions arranged in a circumscribing pattern is also disclosed herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. Nonprovisional patent applicationSer. No. 14/158,809, entitled “Low Profile Load Transducer”, filed onJan. 18, 2014, and further claims the benefit of U.S. Provisional PatentApplication No. 61/887,357, entitled “Low Profile Load Transducer”,filed on Oct. 5, 2013, the disclosure of each of which is herebyincorporated by reference as if set forth in their entirety herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable.

INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the invention relates to multi-component load transducersutilizing multiple strain gage load channels for precise measurement offorces and moments and, more particularly, to beam-style load cellsrequiring an overall small size, high capacity, and yet highsensitivity.

2. Background and Related Art

The use of strain gages in load transducers to measure forces andmoments is a known art. A transducer can incorporate one or more loadchannels. Each load channel measures one of the load components, and iscomprised of one or more strain gages mounted to one or more elasticelements that deform under the applied load. An appropriate circuitryrelates the resistance change in each set of gages to the applied forceor moment. Strain gages have many industrial, medical, and electricalapplications due to their small size, low production cost, flexibilityin installation and use, and high precision.

A typical low profile, small, multi-component load transducer onlyfunctions correctly when the axial (i.e. vertical) force acts relativelycentral to the transducer. Specifications of such transducers indicate amaximum allowable offset for the force being approximately half thediameter of the transducer. Technical specifications of transducers aregiven as the allowable force and moment ratings, where the moment ratingis obtained by multiplying the maximum allowable force with the maximumallowable offset of the force.

Transducers can be used to measure forces and moments in linkages suchas those found in a robotic arm, where the links are connected byjoints, and the magnitude and offset of the forces transmitted by thesejoints are used to control the linkage. In such applications, it isdesirable to have a transducer which has significantly higher momentcapacity than those available in the market. Accordingly, there is aneed for an improved multi-component, low profile load transducer withhigh moment capacity.

When conventional load transducers are utilized in conjunction withforce plates, unique load transducers must be designed and fabricatedfor force plates having a particular footprint size. Consequently, inorder to fit force plates with varying footprint sizes, many differentcustom load transducers are required. These custom load transducerssignificantly increase the material costs associated with thefabrication of a force plate. Also, conventional load transducers oftenspan the full length or width of the force plate component to which theyare mounted, thereby resulting in elongate load transducers that utilizean excessive amount of stock material.

Therefore, what is needed is a load transducer that is capable of beinginterchangeably used with a myriad of different force plate sizes sothat load transducers that are specifically tailored for a particularforce plate size are unnecessary. Moreover, there is a need for auniversal load transducer that is compact and uses less stock materialthan conventional load transducers, thereby resulting in lower materialcosts. Furthermore, there is a need for a force measurement assemblythat utilizes the compact and universal load transducer thereon so as toresult in a more lightweight and portable force measurement assembly.

BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION

Accordingly, the present invention is directed to a load transducer anda force measurement assembly using the same that substantially obviatesone or more problems resulting from the limitations and deficiencies ofthe related art.

In accordance with one or more embodiments of the present invention,there is provided a load transducer that includes a plurality of beamportions connected to one another in succession, the plurality of beamportions being arranged in a circumscribing pattern whereby a centralone of the plurality of beam portions is at least partiallycircumscribed by one or more outer ones of the plurality of beamportions; and at least one load cell disposed on one of the plurality ofbeam portions, the at least one load cell configured to measure at leastone force or moment component of a load applied to the load transducer.

In a further embodiment of the present invention, the at least one loadcell comprises a strain gage configured to measure the at least oneforce or moment component of the load applied to the load transducer.

In yet a further embodiment, the plurality of beam portions are eachpart of a transducer frame, the transducer frame being compact and ofone-piece construction.

In still a further embodiment, the circumscribing pattern in which theplurality of beam portions are arranged is generally G-shaped.

In yet a further embodiment, the circumscribing pattern in which theplurality of beam portions are arranged is generally spiral-shaped.

In still a further embodiment, the at least one load cell comprises atleast three load cells, each of the at least three load cells beingdisposed on a respective one of the plurality of beam portions, a firstof the at least three load cells configured to be sensitive to avertical force component, a second of the at least three load cellsconfigured to be sensitive to a first shear force component, a third ofthe at least three load cells configured to be sensitive to a secondshear force component, the first shear force component being generallyperpendicular to the second shear force component, and each of the firstand second shear force components being generally perpendicular to thevertical force component.

In yet a further embodiment, the plurality of beam portions comprises atleast two pairs of beam portions that are disposed generally parallel toone another.

In still a further embodiment, each of the at least two pairs of beamportions comprises two beam portions that are laterally spaced apartfrom one another by a gap.

In yet a further embodiment, one or more of the plurality of beamportions comprises a first top surface that is disposed at a firstelevation relative to a bottom surface of the load transducer and asecond top surface that is disposed at a second elevation relative tothe bottom surface of the load transducer, the second elevation beinggreater than the first elevation; and wherein a recessed area created bythe difference in elevation between the second elevation and the firstelevation is used to accommodate one or more electrical components ofthe at least one load cell.

In accordance with one or more other embodiments of the presentinvention, there is provided a load transducer that includes a pluralityof beam portions connected to one another in succession, the pluralityof beam portions being arranged in a looped configuration whereby acentral one of the plurality of beam portions emanates from a generallycentral location within a footprint of the load transducer and outerones of the plurality of beam portions are wrapped around the centralone of the plurality of beam portions; and a plurality of load cells,each of the load cells being disposed on a respective one of theplurality of beam portions, the plurality of load cells configured tomeasure one or more force components or one or more moment components,or both one or more force components and one or more moment components.

In a further embodiment of the present invention, the loopedconfiguration in which the plurality of beam portions are arranged isgenerally G-shaped.

In yet a further embodiment, the looped configuration in which theplurality of beam portions are arranged is generally spiral-shaped.

In still a further embodiment, the plurality of load cells comprises atleast three load cells, each of the at least three load cells beingdisposed on a respective one of the plurality of beam portions, a firstof the at least three load cells configured to be sensitive to avertical force component, a second of the at least three load cellsconfigured to be sensitive to a first shear force component, a third ofthe at least three load cells configured to be sensitive to a secondshear force component, the first shear force component being generallyperpendicular to the second shear force component, and each of the firstand second shear force components being generally perpendicular to thevertical force component.

In yet a further embodiment, one or more of the plurality of beamportions comprises a mounting aperture disposed near a respective endthereof for accommodating a fastener.

In still a further embodiment, one or more of the plurality of beamportions comprises an aperture disposed therein and a strain gagedisposed on an outer surface thereof, the outer surface of the one ormore of the plurality of beam portions on which the strain gage isdisposed being generally opposite to an inner surface of the aperture.

In yet a further embodiment, one or more of the plurality of beamportions comprises a first top surface that is disposed at a firstelevation relative to a bottom surface of the load transducer and asecond top surface that is disposed at a second elevation relative tothe bottom surface of the load transducer, the second elevation beinggreater than the first elevation; and wherein a recessed area created bythe difference in elevation between the second elevation and the firstelevation is used to accommodate one or more electrical components ofthe at least one load cell.

In accordance with yet one or more other embodiments of the presentinvention, there is provided a force measurement assembly that includesat least one plate component having a measurement surface for receivinga portion of a body of a subject; and a plurality of load transducers.Each of the plurality of load transducers includes a plurality of beamportions connected to one another in succession, the plurality of beamportions being arranged in a circumscribing pattern whereby a centralone of the plurality of beam portions is at least partiallycircumscribed by one or more outer ones of the plurality of beamportions; and at least one load cell disposed on one of the plurality ofbeam portions, the at least one load cell configured to measure at leastone force or moment component of a load applied to the load transducer.In these one or more other embodiments, one or more of the plurality ofload transducers is disposed proximate to a respective corner of the atleast one plate component.

In a further embodiment of the present invention, none of the pluralityof load transducers extend substantially an entire length or width ofthe at least one plate component.

In yet a further embodiment, at least one of the plurality of loadtransducers comprises a first top surface that is disposed at a firstelevation relative to a bottom surface of the load transducer and asecond top surface that is disposed at a second elevation relative tothe bottom surface of the load transducer, the second elevation beinggreater than the first elevation; and wherein a recessed area created bythe difference in elevation between the second elevation and the firstelevation is used to accommodate one or more electrical components ofthe at least one load cell of the load transducer.

From the foregoing disclosure and the following more detaileddescription of various preferred embodiments it will be apparent tothose skilled in the art that the present invention provides asignificant advance in the technology and art of load transducers.Particularly significant in this regard is the potential the inventionaffords for providing a low profile load transducer with high momentcapacity. Additional features and advantages of various preferredembodiments will be better understood in view of the detaileddescription provided below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention will now be described, by way of example, with referenceto the accompanying drawings, in which:

FIG. 1 is a perspective view of a low profile load transducer, accordingto a first embodiment of the invention;

FIG. 2 is a first side view of the low profile load transducer of FIG.1, according to the first embodiment of the invention;

FIG. 3 is a second side view of the low profile load transducer of FIG.1, according to the first embodiment of the invention;

FIG. 4 is a top view of the low profile load transducer of FIG. 1,according to the first embodiment of the invention;

FIG. 5 is a block diagram illustrating data manipulation operationscarried out by the load transducer data processing system, according toan embodiment of the invention;

FIG. 6 is a perspective view of a low profile load transducer, accordingto a second embodiment of the invention;

FIG. 7 is a first side view of the low profile load transducer of FIG.6, according to the second embodiment of the invention;

FIG. 8 is a second side view of the low profile load transducer of FIG.6, according to the second embodiment of the invention;

FIG. 9 is a top view of the low profile load transducer of FIG. 6,according to the second embodiment of the invention;

FIG. 10 is a perspective view of a low profile load transducer,according to a third embodiment of the invention;

FIG. 11 is a first side view of the low profile load transducer of FIG.10, according to the third embodiment of the invention;

FIG. 12 is a second side view of the low profile load transducer of FIG.10, according to the third embodiment of the invention;

FIG. 13 is a top view of the low profile load transducer of FIG. 10,according to the third embodiment of the invention;

FIG. 14 is a bottom view of the low profile load transducer of FIG. 10,according to the third embodiment of the invention;

FIG. 15 is a perspective view of a low profile load transducer,according to a fourth embodiment of the invention;

FIG. 16 is a first side view of the low profile load transducer of FIG.15, according to the fourth embodiment of the invention;

FIG. 17 is a second side view of the low profile load transducer of FIG.15, according to the fourth embodiment of the invention;

FIG. 18 is a top view of the low profile load transducer of FIG. 15,according to the fourth embodiment of the invention;

FIG. 19 is a perspective view of a low profile load transducer,according to a fifth embodiment of the invention;

FIG. 20 is a perspective view of a low profile load transducer,according to a sixth embodiment of the invention;

FIG. 21 is a perspective view of a low profile load transducer,according to a seventh embodiment of the invention;

FIG. 22 is a perspective view of a low profile load transducer,according to an eighth embodiment of the invention;

FIG. 23 is a perspective view of a low profile load transducer,according to a ninth embodiment of the invention;

FIG. 24 is a perspective view of a low profile load transducer,according to a tenth embodiment of the invention;

FIG. 25 is a perspective view of an exemplary mounting arrangement forthe low profile load transducer illustrated in FIGS. 15-18;

FIG. 26 is a top perspective view of a load transducer, according to aneleventh embodiment of the invention;

FIG. 27 is a first side view of the load transducer of FIG. 26,according to the eleventh embodiment of the invention;

FIG. 28 is a second side view of the load transducer of FIG. 26,according to the eleventh embodiment of the invention;

FIG. 29 is a bottom perspective view of the load transducer of FIG. 26,according to the eleventh embodiment of the invention;

FIG. 30 is a top perspective view of a load transducer, according to atwelfth embodiment of the invention;

FIG. 31 is a first side view of the load transducer of FIG. 30,according to the twelfth embodiment of the invention;

FIG. 32 is a second side view of the load transducer of FIG. 30,according to the twelfth embodiment of the invention;

FIG. 33 is a bottom perspective view of the load transducer of FIG. 30,according to the twelfth embodiment of the invention;

FIG. 34 is a perspective view of a force measurement system thatutilizes the load transducer of FIG. 30, according to an embodiment ofthe invention;

FIG. 35 is a bottom, assembled perspective view of the force measurementassembly of the force measurement system of FIG. 34;

FIG. 36 is a bottom, partially exploded perspective view of the forcemeasurement assembly of the force measurement system of FIG. 34;

FIG. 37 is a block diagram of constituent components of the forcemeasurement system of FIG. 34; and

FIG. 38 is a block diagram illustrating data manipulation operationscarried out by the force measurement system of FIG. 34.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of theinvention. The specific design features of the load transducers asdisclosed herein, including, for example, specific dimensions,orientations, locations, and shapes of the various components, will bedetermined in part by the particular intended application and useenvironment. Certain features of the illustrated embodiments have beenenlarged or distorted relative to others to facilitate visualization andclear understanding. In particular, thin features may be thickened, forexample, for clarity or illustration. All references to direction andposition, unless otherwise indicated, refer to the orientation of theload transducers illustrated in the drawings. In general, up or upwardgenerally refers to an upward direction within the plane of the paper inFIG. 1 and down or downward generally refers to a downward directionwithin the plane of the paper in FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

It will be apparent to those skilled in the art, that is, to those whohave knowledge or experience in this area of technology, that many usesand design variations are possible for the improved load transducersdisclosed herein. The following detailed discussion of variousalternative and preferred embodiments will illustrate the generalprinciples of the invention. Other embodiments suitable for otherapplications will be apparent to those skilled in the art given thebenefit of this disclosure.

Referring now to the drawings, FIGS. 1-4 illustrate a load transducer 10according to a first exemplary embodiment of the present invention. Thisload transducer 10 is designed to have a low profile, small size,trivial weight, high sensitivity, and easy manufacturability. The loadtransducer 10 generally includes a one-piece compact transducer frame 12having a central body portion 14 and a plurality of beams 16, 18, 20,22, 24, 26, 28, 30 extending outwardly from the central body portion 14.As best illustrated in the perspective view of FIG. 1, each of the beams16, 18, 20, 22, 24, 26, 28, 30 comprises a respective load cell ortransducer element for measuring forces and/or moments. For example, theload cells of beams 16, 18, 24, 26 are configured to respectivelymeasure the forces F1, F2, F3, F4 with force vector components F1 _(x),F1 _(y), F1 _(z), F2 _(x), F2 _(y), F2 _(z), F3 _(x), F3 _(y), F3 _(z),F4 _(x), F4 _(y), F4 _(z). In addition to forces, the output of the loadcells can also be used to determine moments and the point of applicationof a force (i.e., its center of pressure). Referring again to FIG. 1, itcan be seen that the illustrated load transducer 10 comprises eightsingle or multi-axis load cells that are mounted to a common structureor body portion 14.

The illustrated transducer frame 12 is shown in FIGS. 1-4. Theillustrated transducer frame 12 includes the central body portion 14 anda plurality of beams 16, 18, 20, 22, 24, 26, 28, 30 extending outwardlytherefrom. In the illustrated embodiment, the transducer frame 12 ismilled as one solid and continuous piece of a single material. That is,the transducer frame 12 is of unitary or one-piece construction with thebody portion 14 and the beams 16, 18, 20, 22, 24, 26, 28, 30 integrallyformed together. The transducer frame 12 is preferably machined in onepiece from aluminum, titanium, steel, or any other suitable materialthat meets strength and weight requirements. Alternatively, the beams16, 18, 20, 22, 24, 26, 28, 30 can be formed separately and attached tothe body portion 14 in any suitable manner.

With reference to FIG. 1, it can be seen that the illustrated centralbody portion 14 is generally in the form of rectangular prism (i.e., asquare prism) with substantially planar top, bottom, and side surfaces.In FIG. 1, it can be seen that the body portion 14 comprises a firstpair of opposed sides 14 a, 14 c and a second pair of opposed sides 14b, 14 d. The side 14 a is disposed generally parallel to the side 14 c,while the side 14 b is disposed generally parallel to the side 14 d.Each of the sides 14 a, 14 b, 14 c, 14 d is disposed generallyperpendicular to the planar top and bottom surfaces. Also, each of thefirst pair of opposed sides 14 a, 14 c is disposed generallyperpendicular to each of the second pair of opposed sides 14 b, 14 d.While not explicitly shown in FIGS. 1-4, the central body portion 14 maycomprise one or more apertures disposed therethrough for accommodatingfasteners (e.g., screws) that attach electronics or circuitry to thebody portion 14. In addition to fasteners, it is noted that any othersuitable means for attachment of the electronics or circuitry canalternatively be utilized (e.g., suitable adhesives, etc.). While theillustrated body portion 14 is generally in the form of a square prism,it is to be understood that the body portion 14 can alternatively haveother suitable shapes.

As shown in FIGS. 1-4, the illustrated beams 16, 18, 20, 22, 24, 26, 28,30 are each attached to one of the sides 14 a, 14 b, 14 c, 14 d of thebody portion 14, and extend generally horizontally outward therefrom. Inparticular, beams 16, 18 extend generally horizontally outward from side14 a of the body portion 14, beams 20, 22 extend generally horizontallyoutward from side 14 b of the body portion 14, beams 24, 26 extendgenerally horizontally outward from side 14 c of the body portion 14,and beams 28, 30 extend generally horizontally outward from side 14 d ofthe body portion 14. In addition, each of the illustrated beams 16, 18,20, 22, 24, 26, 28, 30 extend substantially parallel to the top andbottom surfaces of the body portion 14. Each of the illustrated beams16, 18, 20, 22, 24, 26, 28, 30 has a cantilevered end relative to thebody portion 14 that allows for deflection of the ends of the beams 16,18, 20, 22, 24, 26, 28, 30 in the vertical direction.

With particular reference to FIGS. 1 and 4, it can be seen that thebeams 16, 18 extending from side 14 a are substantially parallel to oneanother, and laterally spaced apart from one another by a gap. Opposedbeams 24, 26, which extend from side 14 c, also are substantiallyparallel to one another, and laterally spaced apart from one another bya gap. Beam 16 extends in a longitudinal direction that is generallyco-linear with, but opposite to the extending direction of beam 26(i.e., both beams 16 and 26 are aligned along central longitudinal axisLA1). Similarly, beam 18 extends in a longitudinal direction that isgenerally co-linear with, but opposite to the extending direction ofbeam 24 (i.e., both beams 18 and 24 are aligned along centrallongitudinal axis LA2). The beams 20, 22 extending from side 14 b aresubstantially parallel to one another, and laterally spaced apart fromone another by a gap. Opposed beams 28, 30, which extend from side 14 d,also are substantially parallel to one another, and laterally spacedapart from one another by a gap. Beam 20 extends in a longitudinaldirection that is generally co-linear with, but opposite to theextending direction of beam 30 (i.e., both beams 20 and 30 are alignedalong central longitudinal axis LA3). Similarly, beam 22 extends in alongitudinal direction that is generally co-linear with, but opposite tothe extending direction of beam 28 (i.e., both beams 22 and 28 arealigned along central longitudinal axis LA4). The illustrated beams 16,18, 20, 22, 24, 26, 28, 30 are provided with generally verticallyextending apertures 32 near their ends for accommodating fasteners thatare used to secure the load transducer 10 to additional structures.Although, it is noted that any other suitable means for attachment ofthe load transducer 10 can alternatively be utilized (e.g., a suitableadhesive for attaching metallic components to one another).

The main body portions of illustrated beams 16, 18, 20, 22, 24, 26, 28,30 have a rectangular-shaped cross section to form generally planar,opposed top and bottom surfaces, and generally planar, opposed sidesurfaces for attachment of load cell components as describedhereinafter. The illustrated beams 16, 18, 20, 22, 24, 26, 28, 30 havegenerally cylindrical end portions, which include the fastener apertures32. As best shown in FIG. 1, the illustrated top planar surfaces of thebeam main body portions of beams 16, 18, 24, 26 are recessed below thetop surfaces of the beam cylindrical end portions to protect the loadcell components from engagement with the structure to which the loadtransducer 10 is attached, while the illustrated bottom planar surfacesof the beam main body portions of beams 20, 22, 28, 30 are recessedabove the bottom surfaces of the beam cylindrical end portions toprotect the load cell components from engagement with the structure towhich the load transducer 10 is attached. In other words, as shown inFIG. 1, the cylindrical end portions of beams 16, 18, 24, 26 areprovided with a top standoff portion (i.e., a cylindrical portionprotruding from the top of each beam having the aperture 32), while thecylindrical end portions of beams 20, 22, 28, 30 are provided with abottom standoff portion (i.e., a cylindrical portion protruding from thebottom of each beam having the aperture 32). While not explicitly shownin the figures, beams 16, 18, 20, 22, 24, 26, 28, 30 may also includeapertures disposed therethrough for increasing the deflectability of thebeams 16, 18, 20, 22, 24, 26, 28, 30 as desired (e.g., the aperturescould be disposed below, or adjacent to each of the strain gages 34, 36,38). In order to accommodate these apertures, the length of each beam16, 18, 20, 22, 24, 26, 28, 30 could be extended so that multiple straingages 34, 36 on a common beam could be spaced apart from one anotheralong a length of the beam (i.e., each strain gage 34, 36 would occupy adedicated, respective segment of the beam). It is noted that theseapertures can be of any suitable size and shape as needed and also canbe eliminated if desired. It is further noted that the beams 16, 18, 20,22, 24, 26, 28, 30 can alternatively have other cross-sectional shapesdepending on whether it is desired to have planar surfaces at the topand/or bottom or left and/or right sides for the load cell componentsbut the illustrated rectangular shape is particularly desirable becausethe same frame can be used for multiple configurations of the transducerload cells.

The illustrated one-piece frame 12 has a low profile or is compact. Theterms “low profile” and “compact” are used in this specification and theclaims to mean that the height is substantially smaller than thefootprint dimensions so that the load transducer 10 can be utilized in amechanical joint without significant changes to the mechanical joint.The illustrated one piece frame 12 has a height H that is about 20% itsfootprint width W₁ or W₂ (see FIGS. 2, 3, 7, and 8). As a result, theload transducer 10 has a low profile or is compact and has a height Hthat is about 20% its footprint width W₁ or W₂. The term “load cell” isused in the specification and claims to mean a load sensing element ofthe load transducer that is capable of sensing one or more loadcomponents of the applied load.

As best shown in FIG. 1, the illustrated load cells are located on beams16, 18, 20, 24, 26, and 30. In the illustrated embodiment, beams 22, 28do not contain any load cells, but, in other embodiments, may containload cells with strain gages 38 similar to beams 20, 30. Beams 16, 26also may contain strain gages 36, similar to beams 18, 24, in otherembodiments. In a preferred embodiment, each load cell comprises one ormore strain gages 34, 36, 38. Specifically, in the illustratedembodiment, beams 16, 18, 24, 26 each comprise a strain gage 34 disposedon the top surface thereof that is sensitive to the vertical forcecomponent (i.e., a F_(Z) strain gage). Opposed beams 18, 24 also eachcomprise a strain gage 36 disposed on a side surface thereof that issensitive to a first shear force component (i.e., a F_(X) strain gage).Opposed beams 20, 30 each comprise a strain gage 38 disposed on a sidesurface thereof that is sensitive to a second shear force component(i.e., a F_(Y) strain gage). All eight (8) of the strain gages 34, 36,38 are measuring a difference in the bending moments in the beams. Ifthe applied shears to each of the two parallel beams 18, 24 or 20, 30are equal (which is most likely the case), this is an optimal number ofstrain gages for a six-component load transducer (i.e., for a loadtransducer that is capable of measuring the three (3) force componentsF_(X), F_(Y), F_(Z) and the three (3) moment components M_(X), M_(Y),M_(Z)). Shear web gages can also be used in lieu of one or more of theillustrated strain gages 34, 36, 38. Also, in other preferredembodiments alternate load and/or moment sensors may be utilized asrequired or desired as long as they do not interfere with the advantagesof the design as a whole. For example, piezoelectric gages orHall-effect sensors are possible alternatives to the strain gages 34,36, 38.

As best shown in FIG. 1, the illustrated load cells are configured asbending beam load cells. The illustrated strain gages 34, 36, 38 aremounted to either top or side surfaces of the beams 16, 18, 20, 24, 26,30 between their attachment locations to the body portion 14 and thecylindrical end portions thereof. Alternatively, the strain gages 34 canbe mounted to the bottom surfaces of the beams 16, 18, 24, 26 betweentheir attachment locations to the body portion 14 and the cylindricalend portions thereof, while the strain gages 36, 38 can be mounted tothe opposite side surfaces of the beams 18, 20, 24, 30 between theirattachment locations to the body portion 14 and the cylindrical endportions thereof. That is, the strain gages 34, 36, 38 are mounted tosurfaces generally normal to the direction of applied vertical and/orshear forces (i.e., F_(X), F_(Y), F_(Z)). It is also noted thatalternatively, the strain gages 34 can be mounted at both the topsurface and the bottom surface of the beams 16, 18, 24, 26, and/or thestrain gages 36, 38 can be mounted at both opposed side surfaces of thebeams 18, 20, 24, 30. These strain gages 34, 36, 38 measure force eitherby bending moment or difference of bending moments at two crosssections. As force is applied to the ends of the beams (e.g., forces F1,F2, F3, F4 with force vector components F1 _(x), F1 _(y), F1 _(z), F2_(x), F2 _(y), F2 _(z), F3 _(x), F3 _(y), F3 _(z), F4 _(x), F4 _(y), F4_(z), applied to the ends of respective beams 16, 18, 24, 26), the beams16, 18, 20, 24, 26, 30 with strain gages attached thereto bend. Thisbending either stretches or compresses the strain gages 34, 36, 38, inturn changing the resistances of the electrical currents passingtherethrough. The amount of change in the electrical voltage or currentis proportional to the magnitude of the applied force (e.g., forces F1,F2, F3, F4 with force vector components F1 _(x), F1 _(y), F1 _(z), F2_(x), F2 _(y), F2 _(z), F3 _(x), F3 _(y), F3 _(z), F4 _(x), F4 _(y), F4_(z), applied to the ends of respective beams 16, 18, 24, 26).

Alternatively, the load cells can be configured as shear-web load cells.In this configuration, the strain gages are mounted to either one of thelateral side surfaces of the beams between their attachment locations tothe body portion 14 and the cylindrical end portions thereof. It isnoted that alternatively, the strain gages can be mounted at both of thelateral side surfaces of the beams. Mounted in these positions, thestrain gages directly measure shear as force is applied to the end ofthe beam.

As best shown in FIG. 1, the load transducer 10 measures applied forces(e.g., forces F1, F2, F3, F4 with force vector components F1 _(x), F1_(y), F1 _(z), F2 _(x), F2 _(y), F2 _(x), F3 _(x), F3 _(y), F3 _(z), F4_(x), F4 _(y), F4 _(z), applied to the ends of respective beams 16, 18,24, 26) at each of the load cells. The sum of the forces is the forcebeing applied to any assembly attached to the top of the load transducer10. The load cells of the beams 16, 26 measure the force being appliedto one lateral side of the load transducer 10; whereas, load cells ofthe beams 18, 24 measure the force being applied to the other lateralside of the load transducer 10. The various moments are determined bysubtracting the sum total of the forces acting on one pair of load cellsfrom the sum total acting upon the opposite pair. For example,subtracting the sum total of the forces acting on load cell of beam 16and load cell of beam 18 from the sum total of the forces acting on loadcell of beam 24 and load cell of beam 26, subtracting the sum total ofload cells of beams 18, 24 from the sum total of load cells of beams 16,26.

The sensory information from the strain gages 34, 36, 38 is transmittedto a microprocessor which could then be used to control the assembly towhich the load transducer is a part of such as a robotic assembly. Asbest shown in FIG. 1, the planar central body portion 14 of thetransducer frame 12 provides an area where associated electronics and/orcircuitry can be mounted. Alternatively, the electronics and/orcircuitry can be mounted at any other suitable location. FIG. 5schematically illustrates exemplary electronic components that can beincluded in the load transducer data processing system. The strain gages34, 36, 38 of load transducer 10 may be electrically connected to asignal amplifier/converter 40, which in turn, is electrically connectedto a computer 42 (i.e., a data acquisition and processing device or adata processing device with a microprocessor). The components 10, 40, 42of the system may be connected either by wiring, or wirelessly to oneanother.

FIG. 5 graphically illustrates the acquisition and processing of theload data carried out by the exemplary load transducer data processingsystem. Initially, as shown in FIG. 5, external forces F1-F4 and/ormoments are applied to the load transducer 10. When the electricalresistance of each strain gage 34, 36, 38 is altered by the applicationof the applied forces and/or moments, the change in the electricalresistance of the strain gages brings about a consequential change inthe output voltage of the strain gage bridge circuit (e.g., a Wheatstonebridge circuit). Thus, in one embodiment, the eight (8) strain gages 34,36, 38 output a total of eight (8) analog output voltages (signals). Insome embodiments, the eight (8) analog output voltages from the eight(8) strain gages 34, 36, 38 are then transmitted to a preamplifier board(not shown) for preconditioning. The preamplifier board is used toincrease the magnitudes of the analog voltage signals, and preferably,to convert the analog voltage signals into digital voltage signals aswell. After which, the load transducer 10 transmits the output signalsS_(TO1)-S_(TO8) to a main signal amplifier/converter 40. Depending onwhether the preamplifier board also includes an analog-to-digital (A/D)converter, the output signals S_(TO1)-S_(TO8) could be either in theform of analog signals or digital signals. The main signalamplifier/converter 40 further magnifies the transducer output signalsS_(TO1)-S_(TO8), and if the signals S_(TO1)-S_(TO8) are of theanalog-type (for a case where the preamplifier board did not include ananalog-to-digital (A/D) converter), it may also convert the analogsignals to digital signals. Then, the signal amplifier/converter 40transmits either the digital or analog signals S_(ACO1)-S_(ACO8) to thedata acquisition/data processing device 42 (computer 42) so that theforces and/or moments that are being applied to the load transducer 10can be transformed into output load values OL. The computer or dataacquisition/data processing device 42 may further comprise ananalog-to-digital (A/D) converter if the signals S_(ACO1)-S_(ACO8) arein the form of analog signals. In such a case, the analog-to-digitalconverter will convert the analog signals into digital signals forprocessing by the microprocessor of the computer 42.

When the computer or data acquisition/data processing device 42 receivesthe voltage signals S_(ACO1)-S_(ACO8), it initially transforms thesignals into output forces and/or moments by multiplying the voltagesignals S_(ACO1)-S_(ACO8) by a calibration matrix. After which, theforce components F_(X), F_(Y), F_(Z) and the moment components M_(X),M_(Y), M_(Z) applied to the load transducer 10 are determined by thecomputer or data acquisition/data processing device 42. Also, the centerof pressure (i.e., the x and y coordinates of the point of applicationof the force applied to the load transducer 10) can be determined by thecomputer or data acquisition/data processing device 42.

FIGS. 6-9 illustrate a load transducer 10′ according to a secondexemplary embodiment of the present invention. With reference to thesefigures, it can be seen that, in some respects, the second exemplaryembodiment is similar to that of the first embodiment. Moreover, someparts are common to both such embodiments. For the sake of brevity, theparts that the second embodiment of the load transducer has in commonwith the first embodiment will only be briefly mentioned, if at all,because these components have already been explained in detail above.Furthermore, in the interest of clarity, these components will bedenoted using the same reference characters that were used in the firstembodiment.

Initially, referring to the perspective view of FIG. 6, it can be seenthat, like the first exemplary embodiment, the transducer frame 12′ ofthe second embodiment includes a central body portion 14 and a pluralityof beams 16, 18, 20′, 24′, 28, 30 extending outwardly therefrom.Although, unlike the first exemplary embodiment of the load transducer,the side 14 b of the body portion 14 of the load transducer 10′ containsonly a single beam 20′ extending therefrom, rather two beams 20, 22 (seeFIG. 1). Similarly, unlike the load transducer 10 of the firstembodiment, the side 14 c of the body portion 14 of the load transducer10′ contains only a single beam 24′ extending therefrom, rather twobeams 24, 26 (refer to FIG. 1). Also, unlike the load transducer 10 ofthe first embodiment, the load transducer 10′ includes only three straingages 34 that are sensitive to the vertical force component (i.e., threeF_(Z) strain gages), rather than four strain gages.

In particular, in the second embodiment, beams 16, 18, 24′ each comprisea strain gage 34 disposed on the top surface thereof that is sensitiveto the vertical force component (i.e., a F_(Z) strain gage). Beams 18,24′ also each comprise a strain gage 36 disposed on a side surfacethereof that is sensitive to a first shear force component (i.e., aF_(X) strain gage), while beams 20′, 30 each comprise a strain gage 38disposed on a side surface thereof that is sensitive to a second shearforce component (i.e., a F_(Y) strain gage). The load transducer 10′ ofthe second embodiment is capable of measuring the three force components(F_(X), F_(Y), F_(Z)) and the three moment components (M_(X), M_(Y),M_(Z)) with a minimum of six beams 16, 18, 20′, 24′, 28, 30 (i.e., threeinput beams and three output beams) and a minimum of seven strain gages34, 36, 38.

Now, with reference to the top view illustrated in FIG. 9, it can beseen that the central longitudinal axis LA5 of the beam 20′, whichextends from side 14 b of the body portion 14, is generally equallyspaced apart from the central longitudinal axis LA3 and LA4 (i.e., thecentral longitudinal axis LA5 of the beam 20′ is generally centeredbetween the central longitudinal axis LA3 of beam 30 and the centrallongitudinal axis LA4 of beam 28). Similarly, as shown in FIG. 9, thelongitudinal axis LA6 of the beam 24′, which extends from side 14 c ofthe body portion 14, is generally equally spaced apart from the centrallongitudinal axis LA1 and LA2 (i.e., the central longitudinal axis LA6of the beam 24′ is generally centered between the central longitudinalaxis LA1 of beam 16 and the central longitudinal axis LA2 of beam 18).The other features of the load transducer 10′ are similar to that of theload transducer 10, and thus, need not be reiterated herein.

FIGS. 10-14 illustrate a load transducer 100 according to a thirdexemplary embodiment of the present invention. Referring initially tothe perspective view of FIG. 10, it can be seen that the load transducer100 generally includes a one-piece compact transducer frame 112 having acentral body portion 114 and a plurality of generally U-shapedtransducer beams 116, 118, 120, 122 extending outwardly from the centralbody portion 114. As best illustrated in FIG. 10, each of the beams 116,118, 120, 122 comprises a plurality of load cells or transducer elementsfor measuring forces and/or moments.

With reference again to FIG. 10, it can be seen that the illustratedcentral body portion 114 is generally in the form of square band-shapedelement with a central opening 102 disposed therethrough. In FIG. 10, itcan be seen that the body portion 114 comprises a first pair of opposedsides 114 a, 114 c and a second pair of opposed sides 114 b, 114 d. Theside 114 a is disposed generally parallel to the side 114 c, while theside 114 b is disposed generally parallel to the side 114 d. Each of thesides 114 a, 114 b, 114 c, 114 d is disposed generally perpendicular tothe planar top and bottom surfaces of the body portion 114. Also, eachof the first pair of opposed sides 114 a, 114 c is disposed generallyperpendicular to each of the second pair of opposed sides 114 b, 114 d.In addition, as shown in FIG. 10, each of the opposed sides 114 a, 114 ccomprises a beam connecting portion 128 extending outward therefrom. Inthe illustrated embodiment, it can be seen that each of the beamconnecting portions 128 comprises a plurality of apertures 130 (e.g.,two apertures 130) disposed therethrough for accommodating fasteners(e.g., screws) that attach the load transducer 100 to another object,such as a robotic arm, etc. Also, as depicted in the side views of FIGS.11 and 12 and the bottom view of FIG. 14, the bottom surface of thecentral body portion 114 comprises a raised portion or standoff portion126 for elevating the transducer beams 116, 118, 120, 122 above theobject (e.g., robotic arm) to which the load transducer 100 is attachedso that forces and/or moments are capable of being accurately measuredby the load transducer 100. In one or more embodiments, the structuralcomponents to which the load transducer 100 is mounted are connectedonly to the top standoff portions 124 and the bottom standoff 126 so asto ensure that the total load applied to the load transducer 100 istransmitted through the transducer beams 116, 118, 120, 122.

As shown in FIGS. 10-14, the illustrated generally U-shaped transducerbeams 116, 118, 120, 122 are each attached to one of the sides 114 a,114 b, 114 c, 114 d of the body portion 114 via a connecting portion128, and extend generally horizontally outward therefrom. In particular,beams 116, 118 extend generally horizontally outward from opposed sidesof the beam connecting portion 128 attached to side 114 a of the bodyportion 114, while the beams 120, 122 extend generally horizontallyoutward from opposed sides of the beam connecting portion 128 attachedto side 114 c of the body portion 114. As best shown in FIG. 10, the topand bottom surfaces of each of the illustrated beams 116, 118, 120, 122are disposed substantially co-planar with the top and bottom surfaces ofthe body portion 114. Each of the illustrated beams 116, 118, 120, 122has a U-shaped cantilevered end relative to the body portion 114 thatallows for deflection of the ends of the beams in multiple directions.

With particular reference to FIGS. 10, 13, and 14, it can be seen thateach of the generally U-shaped beams 116, 118, 120, 122 comprises aplurality of segmental beam portions, wherein each of the successivebeam portions are disposed substantially perpendicular to theimmediately preceding beam portion. For example, as shown in FIG. 10,the first generally U-shaped transducer beam 116 comprises a first beamportion 116 a extending from a first side of the beam connecting portion128, a second beam portion 116 b connected to the first beam portion 116a and disposed substantially perpendicular thereto, a third beam portion116 c connected to the second beam portion 116 b and disposedsubstantially perpendicular thereto, and a fourth beam portion 116 dconnected to the third beam portion 116 c and disposed substantiallyperpendicular thereto. Similarly, the second generally U-shapedtransducer beam 118 comprises a first beam portion 118 a extending froma second side of the beam connecting portion 128 (which is generallyopposite to the first side of the beam connecting portion 128 from whichthe first beam portion 116 a extends), a second beam portion 118 bconnected to the first beam portion 118 a and disposed substantiallyperpendicular thereto, a third beam portion 118 c connected to thesecond beam portion 118 b and disposed substantially perpendicularthereto, and a fourth beam portion 118 d connected to the third beamportion 118 c and disposed substantially perpendicular thereto. Withreference to FIGS. 10, 13, and 14, it can be seen that the generallyU-shaped transducer beams 120, 122 are generally minor images of thegenerally U-shaped transducer beams 116, 118, and thus, have the samestructure as the generally U-shaped transducer beams 116, 118. Referringagain to FIGS. 10, 13, and 14, it can be seen that the fourth beamportion of each of the generally U-shaped transducer beams 116, 118,120, 122 comprises a raised portion or standoff portion 124 withmounting apertures 132 (e.g., two apertures 132) disposed therethroughfor accommodating fasteners (e.g., screws) that attach the loadtransducer 100 to another object, such as a robotic arm, etc. Inaddition, as shown in FIGS. 10 and 13, each generally U-shapedtransducer beam 116, 118, 120, 122 comprises a central beam gap 106,which is bounded by the second, third, and fourth beam portions. Also,it can be seen that the first and second beam portions of eachtransducer beam 116, 118, 120, 122 are separated from the opposing sidesof the central body portion 114 by an L-shaped gap 104. That is, thesides of the central body portion 114, which face the sides of the firstand second beam portions in an opposing relationship, are separated fromthe sides of the first and second beam portions by the L-shaped gap 104.

As best shown in the perspective view of FIG. 10, the illustrated loadcells are located on the transducer beams 116, 118, 120, 122. In theillustrated embodiment, each load cell comprises a plurality of straingages 134, 136, 138. Specifically, in the illustrated embodiment, eachof the first portions (e.g., 116 a, 118 a) of the transducer beams 116,118, 120, 122 comprise a strain gage 134 disposed on the top surfacethereof that is sensitive to the vertical force component (i.e., a F_(Z)strain gage). The first portions (e.g., 116 a, 118 a) of the transducerbeams 116, 118, 120, 122 also each comprise a strain gage 138 disposedon a side surface thereof that is sensitive to a first shear forcecomponent (i.e., a F_(Y) strain gage). Also, in the illustratedembodiment, each of the fourth portions (e.g., 116 d, 118 d) of thetransducer beams 116, 118, 120, 122 comprise a strain gage 136 disposedon a side surface thereof that is sensitive to a second shear forcecomponent (i.e., a F_(X) strain gage).

As best shown in FIG. 10, the illustrated load cells are configured asbending beam load cells. The illustrated strain gages 134, 136, 138 aremounted to either top or side surfaces of the beams 116, 118, 120, 122between their attachment locations to the beam connecting portions 128and the raised end portions 124 thereof. Alternatively, the strain gages134 can be mounted to the bottom surfaces of the first beam portions(e.g., 116 a, 118 a) of the transducer beams 116, 118, 120, 122, whilethe strain gages 138 can be mounted to the opposite side surfaces of thefirst beam portions (e.g., 116 a, 118 a) of the transducer beams 116,118, 120, 122. Similarly, the strain gages 136 can be mounted to theopposite side surfaces of the fourth beam portions (e.g., 116 d, 118 d)of the transducer beams 116, 118, 120, 122. In general, the strain gages134, 136, 138 are mounted to surfaces generally normal to the directionof applied vertical and/or shear forces (i.e., F_(X), F_(Y), F_(Z)). Itis also noted that alternatively, the strain gages 134 can be mounted atboth the top surface and the bottom surface of the first beam portionsof the beams 116, 118, 120, 122, the strain gages 138 can be mounted atboth opposed side surfaces of first beam portions of the beams 116, 118,120, 122, and/or the strain gages 136 can be mounted at both opposedside surfaces of the beams 116, 118, 120, 122. These strain gages 134,136, 138 measure force either by bending moment or difference of bendingmoments at two cross sections. As force is applied to the ends of thebeams, the beams 116, 118, 120, 122 bend. This bending either stretchesor compresses the strain gages 134, 136, 138, which in turn changes theresistance of the electrical current passing therethrough. The amount ofchange in the electrical voltage or current is proportional to themagnitude of the applied force, as applied to the ends of respectivebeams 116, 118, 120, 122.

Next, referring to FIGS. 15-18, a load transducer 200 according to afourth exemplary embodiment of the present invention will be described.Referring initially to the perspective view of FIG. 15, it can be seenthat the load transducer 200 generally includes a one-piece compacttransducer frame 204 that is generally in the form of square band-shapedelement with a central opening 202 disposed therethrough. As bestillustrated in FIGS. 15 and 18, the square band-shaped transducer frame204 comprises a first transducer beam side portion 206, a secondtransducer beam side portion 208, a third transducer beam side portion210, and a fourth transducer beam side portion 212. Also, as shown inFIG. 15, the transducer beam side portions 206, 208, 210, 212 comprise aplurality of load cells or transducer elements for measuring forcesand/or moments. The transducer frame 204 of the load transducer 200 issimilar to the other transducers (e.g., transducers 300, 400) that willbe described hereinafter, except that the central body portion of thesetransducers (e.g., 300, 400) has been removed in the load transducer200.

As shown in FIGS. 15-18, the illustrated transducer beam side portions206, 208, 210, 212 of the transducer frame 204 are arranged in agenerally square configuration. In particular, with reference to FIGS.15 and 18, the first transducer beam side portion 206 is connected tothe second transducer beam side portion 208 on one of its longitudinalends, and the fourth transducer beam side portion 212 on the other oneof its longitudinal ends, and the first transducer beam side portion 206is disposed generally perpendicular to each of the second and fourthtransducer beam side portions 208, 212. The second transducer beam sideportion 208 is connected to the first transducer beam side portion 206on one of its longitudinal ends, and the third transducer beam sideportion 210 on the other one of its longitudinal ends, and the secondtransducer beam side portion 208 is disposed generally perpendicular toeach of the first and third transducer beam side portions 206, 210. Thethird transducer beam side portion 210 is connected to the secondtransducer beam side portion 208 on one of its longitudinal ends, andthe fourth transducer beam side portion 212 on the other one of itslongitudinal ends, and the third transducer beam side portion 210 isdisposed generally perpendicular to each of the second and fourthtransducer beam side portions 208, 212. The fourth transducer beam sideportion 212 is connected to the third transducer beam side portion 210on one of its longitudinal ends, and the first transducer beam sideportion 206 on the other one of its longitudinal ends, and the fourthtransducer beam side portion 212 is disposed generally perpendicular toeach of the first and third transducer beam side portions 206, 210.Referring to FIGS. 15, 17, and 18, it can be seen that the top surfaceof the second transducer beam side portion 208 and the top surface ofthe fourth transducer beam side portion 212 each comprises a centralraised portion or standoff portion 214 with spaced apart mountingapertures 218 (e.g., two spaced apart apertures 218) disposedtherethrough for accommodating fasteners (e.g., screws) that attach theload transducer 200 to another object, such as a robotic arm, etc.Similarly, with reference to FIGS. 15 and 16, it can be seen that thebottom surface of the first transducer beam side portion 206 and thebottom surface of the third transducer beam side portion 210 eachcomprises a central raised portion or standoff portion 216 with spacedapart mounting apertures 218 (e.g., two spaced apart apertures 218)disposed therethrough for accommodating fasteners (e.g., screws) thatattach the load transducer 200 to another object, such as a robotic arm,etc.

As best shown in the perspective view of FIG. 15, the illustrated loadcells are located on the transducer beam side portions 206, 208, 210,212. In the illustrated embodiment, each load cell comprises one or morestrain gages 220, 222, 224. Specifically, in the illustrated embodiment,the first transducer beam side portion 206 and the third transducer beamside portion 210 each comprise a plurality of spaced apart strain gages220 (e.g., two spaced apart strain gages 220) disposed on the topsurface thereof that is sensitive to the vertical force component (i.e.,a F_(Z) strain gage). The second transducer beam side portion 208 andthe fourth transducer beam side portion 212 also each comprise aplurality of spaced apart strain gages 222 (e.g., two spaced apartstrain gages 222) disposed on a side surface thereof that is sensitiveto a first shear force component (i.e., a F_(X) strain gage). Also, inthe illustrated embodiment, the first transducer beam side portion 206and the third transducer beam side portion 210 also each comprise aplurality of spaced apart strain gages 224 (e.g., two spaced apartstrain gages 224) disposed on a side surface thereof that is sensitiveto a second shear force component (i.e., a F_(Y) strain gage).

As best shown in FIG. 15, the illustrated load cells are configured asbending beam load cells. The illustrated strain gages 220, 222, 224 aremounted to either top or side surfaces of the transducer beam sideportions 206, 208, 210, 212 between the opposed longitudinal endsthereof. Alternatively, the strain gages 220 can be mounted to thebottom surfaces of the first and third transducer beam side portions206, 210, while the strain gages 222 can be mounted to the opposite sidesurfaces of the second and fourth transducer beam side portions 208,212. Similarly, the strain gages 224 can be mounted to the opposite sidesurfaces of the first and third transducer beam side portions 206, 210.In general, the strain gages 220, 222, 224 are mounted to surfacesgenerally normal to the direction of applied vertical and/or shearforces (i.e., F_(X), F_(Y), F_(Z)). It is also noted that alternatively,the strain gages 220 can be mounted at both the top surface and thebottom surface of the first and third transducer beam side portions 206,210, the strain gages 222 can be mounted at both opposed side surfacesof second and fourth transducer beam side portions 208, 212, and/or thestrain gages 224 can be mounted at both opposed side surfaces of thefirst and third transducer beam side portions 206, 210. These straingages 220, 222, 224 measure force either by bending moment or differenceof bending moments at two cross sections. As force is applied to thebeams, the beams 206, 208, 210, 212 bend. This bending either stretchesor compresses the strain gages 220, 222, 224, which in turn changes theresistance of the electrical current passing therethrough. The amount ofchange in the electrical voltage or current is proportional to themagnitude of the applied force, as transferred through the end portionsof respective beams 206, 208, 210, 212.

An exemplary mounting arrangement for the load transducer 200 isillustrated in FIG. 25. As depicted in the perspective view of FIG. 25,the load transducer 200 is mounted between a top plate member 226 and abottom plate member 228. Specifically, in this mounting arrangement, thebottom surface 226 a of the top plate member 226 abuts the top surfacesof the standoff portions 214 on the second and fourth transducer beamside portions 208, 212, while the top surface 228 a of the bottom platemember 228 abuts the bottom surfaces of the standoff portions 216 on thefirst and third transducer beam side portions 206, 210. As such, in thismounting arrangement, an upper gap 230 is formed between the topsurfaces of the load transducer 200 and the bottom surface 226 a of thetop plate member 226 by the two spaced apart top standoff portions 214.Similarly, a lower gap 232 is formed between the bottom surfaces of theload transducer 200 and the top surface 228 a of the bottom plate member228 by the two spaced apart bottom standoff portions 216. Thus, asresult of the mounting arrangement illustrated in FIG. 25, the entireload exerted on the load transducer 200 by the top and bottom platemembers 226, 228 is transferred through the corner portions of thetransducer frame 204, which are instrumented with the strain gages 220,222, 224 and are spaced apart from the top and bottom plate members 226,228 by the standoff portions 214, 216.

While the exemplary mounting arrangement is illustrated in FIG. 25 usingthe load transducer 200, it is to be understood that each of the otherload transducers 10, 10′, 100, 300, 400, 500, 600, 700, 800 describedherein are mounted in generally the same manner to adjoining structures(e.g., plate members 226, 228 or components of a robotic arm). That is,the standoff portions described on the load transducers 10, 10′, 100,300, 400, 500, 600, 700, 800 perform the same functions as thosedescribed in conjunction with the load transducer 200 above. Inparticular, the adjoining structures to which the transducers aremounted are only connected to the top standoff portions and the bottomstandoff portions of each load transducer 10, 10′, 100, 300, 400, 500,600, 700, 800 so as to ensure that the total loads applied to the loadtransducers 10, 10′, 100, 300, 400, 500, 600, 700, 800 are transmittedthrough the instrumented portions of the transducer beams of thetransducers.

FIG. 19 illustrates a load transducer 300 according to a fifth exemplaryembodiment of the present invention. With reference to this figure, itcan be seen that, in some respects, the fifth exemplary embodiment issimilar to that of the fourth embodiment. Moreover, some parts arecommon to both such embodiments. For the sake of brevity, the parts thatthe fifth embodiment of the load transducer has in common with thefourth embodiment will only be briefly mentioned because thesecomponents have already been explained in detail above.

Initially, referring to the perspective view of FIG. 19, it can be seenthat, unlike the fourth exemplary embodiment of the load transducer, theload transducer 300 comprises a central body portion 302. Also, unlikethe load transducer 200 of the fourth embodiment, the second and fourthtransducer beam side portions 308, 312 have side projecting portions 326extending from the inner sides thereof towards the central body portion302. As shown in FIG. 19, the load transducer 300 generally includes aone-piece compact transducer frame 304 with a central body portion 302and a plurality of transducer beam side portions 306, 308, 310, 312.

With reference again to FIG. 19, it can be seen that the illustratedcentral body portion 302 is generally in the form of rectangularband-shaped element with a central opening 303 disposed therethrough. InFIG. 19, it can be seen that the body portion 302 comprises a first pairof opposed side portions 302 a, 302 c and a second pair of opposed sideportions 302 b, 302 d. The side portion 302 a is disposed generallyparallel to the side portion 302 c, while the side portion 302 b isdisposed generally parallel to the side portion 302 d. Each of the sidesurfaces of the side portions 302 a, 302 b, 302 c, 302 d is disposedgenerally perpendicular to the planar top and bottom surfaces thereof.Also, each of the first pair of opposed side portions 302 a, 302 c isdisposed generally perpendicular to each of the second pair of opposedsides portions 302 b, 302 d. In addition, as shown in FIG. 19, each ofthe opposed side portions 302 a, 302 c forms a middle portion of thefirst and third transducer beam side portions 306, 310. In theillustrated embodiment, it can be seen that each of the opposed sideportions 302 a, 302 c comprises a plurality of apertures 318 (e.g., twoapertures 318) disposed therethrough for accommodating fasteners (e.g.,screws) that attach the load transducer 300 to another object, such as arobotic arm, etc. Also, as depicted in the FIG. 19, the central bodyportion 302 comprises a raised top portion or top standoff portion 314for spacing the transducer beam side portions 306, 308, 310, 312 apartfrom the object (e.g., robotic arm) to which the load transducer 300 isattached so that forces and/or moments are capable of being accuratelymeasured by the load transducer 300.

As shown in FIG. 19, the illustrated transducer beam side portions 306,308, 310, 312 of the transducer frame 304 are arranged in a generallysquare configuration. In particular, with reference to FIG. 19, thefirst transducer beam side portion 306 is connected to the secondtransducer beam side portion 308 on one of its longitudinal ends, andthe fourth transducer beam side portion 312 on the other one of itslongitudinal ends, and the first transducer beam side portion 306 isdisposed generally perpendicular to each of the second and fourthtransducer beam side portions 308, 312. The second transducer beam sideportion 308 is connected to the first transducer beam side portion 306on one of its longitudinal ends, and the third transducer beam sideportion 310 on the other one of its longitudinal ends, and the secondtransducer beam side portion 308 is disposed generally perpendicular toeach of the first and third transducer beam side portions 306, 310. Thethird transducer beam side portion 310 is connected to the secondtransducer beam side portion 308 on one of its longitudinal ends, andthe fourth transducer beam side portion 312 on the other one of itslongitudinal ends, and the third transducer beam side portion 310 isdisposed generally perpendicular to each of the second and fourthtransducer beam side portions 308, 312. The fourth transducer beam sideportion 312 is connected to the third transducer beam side portion 310on one of its longitudinal ends, and the first transducer beam sideportion 306 on the other one of its longitudinal ends, and the fourthtransducer beam side portion 312 is disposed generally perpendicular toeach of the first and third transducer beam side portions 306, 310.Referring to FIG. 19, it can be seen that the bottom surface of thesecond transducer beam side portion 308 and the bottom surface of thefourth transducer beam side portion 312 each comprises a centralstandoff portion 316, which is connected to the side projecting portion326 on each of the transducer beam side portions 308, 312. The sideprojecting portions 326 each comprise spaced apart mounting apertures328 (e.g., two spaced apart apertures 328) disposed therethrough foraccommodating fasteners (e.g., screws) that attach the load transducer300 to another object, such as a robotic arm, etc.

As best shown in the perspective view of FIG. 19, the illustrated loadcells are located on the transducer beam side portions 306, 308, 310,312. In the illustrated embodiment, each load cell comprises one or morestrain gages 320, 322, 324. Specifically, in the illustrated embodiment,the second transducer beam side portion 308 and the fourth transducerbeam side portion 312 each comprise a plurality of spaced apart straingages 320 (e.g., two spaced apart strain gages 320) disposed on the topsurface thereof that is sensitive to the vertical force component (i.e.,a F_(Z) strain gage). The second transducer beam side portion 308 andfourth transducer beam side portion 312 also each comprise a pluralityof spaced apart strain gages 322 (e.g., two spaced apart strain gages322) disposed on a side surface thereof that is sensitive to a firstshear force component (i.e., a F_(X) strain gage). Also, in theillustrated embodiment, the first transducer beam side portion 306 andthe third transducer beam side portion 310 also each comprise aplurality of spaced apart strain gages 324 (e.g., two spaced apartstrain gages 324) disposed on a side surface thereof that is sensitiveto a second shear force component (i.e., a F_(Y) strain gage).

FIG. 20 illustrates a load transducer 400 according to a sixth exemplaryembodiment of the present invention. With reference to this figure, itcan be seen that, in some respects, the sixth exemplary embodiment issimilar to that of the fifth embodiment. Moreover, some parts are commonto both such embodiments. For the sake of brevity, the parts that thesixth embodiment of the load transducer has in common with the fifthembodiment will only be briefly mentioned because these components havealready been explained in detail above.

Initially, referring to the perspective view of FIG. 20, it can be seenthat, unlike the fifth exemplary embodiment of the load transducer, allfour sides of the central body portion 402 of the load transducer 400are spaced apart from the transducer beam side portions 406, 408, 410,412. In particular, the central body portion 402 is spaced apart fromthe transducer beam side portions 406, 408, 410, 412 by the two C-shapedgaps 426. Also, unlike the load transducer 300 of the fifth embodiment,the first and third transducer beam side portions 406, 410 of the loadtransducer 400 are connected to the central body portion 402 by the beamconnecting portions 417. Although, like the load transducer 300, theload transducer 400 generally includes a one-piece compact transducerframe 404 with a central body portion 402 and a plurality of transducerbeam side portions 406, 408, 410, 412.

With reference again to FIG. 20, it can be seen that the illustratedcentral body portion 402 is generally in the form of rectangularband-shaped element with a central opening 403 disposed therethrough. InFIG. 20, it can be seen that the body portion 402 comprises a first pairof opposed side portions 402 a, 402 c and a second pair of opposed sideportions 402 b, 402 d. The side portion 402 a is disposed generallyparallel to the side portion 402 c, while the side portion 402 b isdisposed generally parallel to the side portion 402 d. Each of the sidesurfaces of the side portions 402 a, 402 b, 402 c, 402 d is disposedgenerally perpendicular to the planar top and bottom surfaces thereof.Also, each of the first pair of opposed side portions 402 a, 402 c isdisposed generally perpendicular to each of the second pair of opposedsides portions 402 b, 402 d. In addition, as shown in FIG. 20, each ofthe opposed side portions 402 a, 402 c is connected to the first andthird transducer beam side portions 406, 410 by beam connecting portions417. In the illustrated embodiment, it can be seen that each of the beamconnecting portions 417 comprises a plurality of apertures 418 (e.g.,two apertures 418) disposed therethrough for accommodating fasteners(e.g., screws) that attach the load transducer 400 to another object,such as a robotic arm, etc.

As shown in FIG. 20, the illustrated transducer beam side portions 406,408, 410, 412 of the transducer frame 404 are arranged in a generallysquare configuration. In particular, with reference to FIG. 20, thefirst transducer beam side portion 406 is connected to the secondtransducer beam side portion 408 on one of its longitudinal ends, andthe fourth transducer beam side portion 412 on the other one of itslongitudinal ends, and the first transducer beam side portion 406 isdisposed generally perpendicular to each of the second and fourthtransducer beam side portions 408, 412. The second transducer beam sideportion 408 is connected to the first transducer beam side portion 406on one of its longitudinal ends, and the third transducer beam sideportion 410 on the other one of its longitudinal ends, and the secondtransducer beam side portion 408 is disposed generally perpendicular toeach of the first and third transducer beam side portions 406, 410. Thethird transducer beam side portion 410 is connected to the secondtransducer beam side portion 408 on one of its longitudinal ends, andthe fourth transducer beam side portion 412 on the other one of itslongitudinal ends, and the third transducer beam side portion 410 isdisposed generally perpendicular to each of the second and fourthtransducer beam side portions 408, 412. The fourth transducer beam sideportion 412 is connected to the third transducer beam side portion 410on one of its longitudinal ends, and the first transducer beam sideportion 406 on the other one of its longitudinal ends, and the fourthtransducer beam side portion 412 is disposed generally perpendicular toeach of the first and third transducer beam side portions 406, 410.Referring to FIG. 20, it can be seen that the top surface of the secondtransducer beam side portion 408 and the top surface of the fourthtransducer beam side portion 412 each comprises a central raised portionor standoff portion 414 with spaced apart mounting apertures 428 (e.g.,two spaced apart apertures 428) disposed therethrough for accommodatingfasteners (e.g., screws) that attach the load transducer 400 to anotherobject, such as a robotic arm, etc. Similarly, with reference to FIG.20, it can be seen that the bottom surface of the first transducer beamside portion 406 and the bottom surface of the third transducer beamside portion 410 each comprises a central raised portion or standoffportion 416.

As best shown in the perspective view of FIG. 20, the illustrated loadcells are located on the transducer beam side portions 406, 408, 410,412. In the illustrated embodiment, each load cell comprises one or morestrain gages 420, 422, 424. Specifically, in the illustrated embodiment,the first transducer beam side portion 406 and the third transducer beamside portion 410 each comprise a plurality of spaced apart strain gages420 (e.g., two spaced apart strain gages 420) disposed on the topsurface thereof that is sensitive to the vertical force component (i.e.,a F_(Z) strain gage). The second transducer beam side portion 408 andfourth transducer beam side portion 412 also each comprise a pluralityof spaced apart strain gages 422 (e.g., two spaced apart strain gages422) disposed on a side surface thereof that is sensitive to a firstshear force component (i.e., a F_(X) strain gage). Also, in theillustrated embodiment, the first transducer beam side portion 406 andthe third transducer beam side portion 410 also each comprise aplurality of spaced apart strain gages 424 (e.g., two spaced apartstrain gages 424) disposed on a side surface thereof that is sensitiveto a second shear force component (i.e., a F_(Y) strain gage).

FIG. 21 illustrates a load transducer 500 according to a seventhexemplary embodiment of the present invention. With reference to thisfigure, it can be seen that, in some respects, the seventh exemplaryembodiment is similar to that of the fifth embodiment. Moreover, someparts are common to both such embodiments. For the sake of brevity, theparts that the seventh embodiment of the load transducer has in commonwith the fifth embodiment will only be briefly mentioned because thesecomponents have already been explained in detail above.

Initially, referring to the perspective view of FIG. 21, it can be seenthat, like the fifth embodiment described above, the load transducer 500generally includes a one-piece compact transducer frame 504 with acentral body portion 502 and a plurality of transducer beam sideportions 506, 508, 510, 512, 514, 516. Although, the central bodyportion 502 of the load transducer 500 is considerably wider than thecentral body portion 302 of the load transducer 300.

With reference again to FIG. 21, it can be seen that the illustratedcentral body portion 502 is generally in the form of square band-shapedelement with a central opening 530 disposed therethrough. In FIG. 21, itcan be seen that the body portion 502 comprises a first pair of opposedside portions 502 a, 502 c and a second pair of opposed side portions502 b, 502 d. The side portion 502 a is disposed generally parallel tothe side portion 502 c, while the side portion 502 b is disposedgenerally parallel to the side portion 502 d. Each of the side surfacesof the side portions 502 a, 502 b, 502 c, 502 d is disposed generallyperpendicular to the planar top and bottom surfaces thereof. Also, eachof the first pair of opposed side portions 502 a, 502 c is disposedgenerally perpendicular to each of the second pair of opposed sidesportions 502 b, 502 d. In addition, as shown in FIG. 21, each of theopposed side portions 502 a, 502 c is disposed between a respective pairof transducer beam side portions 506, 508 and 512, 514. In theillustrated embodiment, it can be seen that each of the opposed sideportions 502 a, 502 c comprises a plurality of apertures 532 (e.g., twoapertures 532) disposed therethrough for accommodating fasteners (e.g.,screws) that attach the load transducer 500 to another object, such as arobotic arm, etc. Also, as depicted in the FIG. 21, the central bodyportion 502 comprises a raised bottom portion or bottom standoff portion520 for spacing the transducer beam side portions 506, 508, 510, 512,514, 516 apart from the object (e.g., robotic arm) to which the loadtransducer 500 is attached so that forces and/or moments are capable ofbeing accurately measured by the load transducer 500.

As shown in FIG. 21, the first set of illustrated transducer beam sideportions 506, 514, 516 of the transducer frame 504 are arranged in agenerally C-shaped configuration on a first side of the central bodyportion 502. A first side aperture 534 is formed between the sideportion 502 d of the central body portion 502 and the first set oftransducer beam side portions 506, 514, 516. Referring again to FIG. 21,it can be seen that the first transducer beam side portion 506 isconnected to the sixth transducer beam side portion 516 on one of itslongitudinal ends, and the side portion 502 d of the central bodyportion 502 on the other one of its longitudinal ends, and the firsttransducer beam side portion 506 is disposed generally perpendicular tothe side portion 502 d of the central body portion 502 and to sixthtransducer beam side portion 516. Similarly, the fifth transducer beamside portion 514 is connected to the sixth transducer beam side portion516 on one of its longitudinal ends, and the side portion 502 d of thecentral body portion 502 on the other one of its longitudinal ends, andthe fifth transducer beam side portion 514 is disposed generallyperpendicular to the side portion 502 d of the central body portion 502and to sixth transducer beam side portion 516. The sixth transducer beamside portion 516 is connected to the first transducer beam side portion506 on one of its longitudinal ends, and the fifth transducer beam sideportion 514 on the other one of its longitudinal ends, and the sixthtransducer beam side portion 516 is disposed generally perpendicular toeach of the first and fifth transducer beam side portions 506, 514.Turning again to FIG. 21, it can be seen that the second set oftransducer beam side portions 508, 510, 512 of the transducer frame 504is arranged in a generally C-shaped configuration on a second side ofthe central body portion 502, which is opposite to the first side of thecentral body portion 502. A second side aperture 534 is formed betweenthe side portion 502 b of the central body portion 502 and the secondset of transducer beam side portions 508, 510, 512. In FIG. 21, it canbe seen that the second transducer beam side portion 508 is connected tothe third transducer beam side portion 510 on one of its longitudinalends, and the side portion 502 b of the central body portion 502 on theother one of its longitudinal ends, and the second transducer beam sideportion 508 is disposed generally perpendicular to the side portion 502b of the central body portion 502 and to third transducer beam sideportion 510. Similarly, the fourth transducer beam side portion 512 isconnected to the third transducer beam side portion 510 on one of itslongitudinal ends, and the side portion 502 b of the central bodyportion 502 on the other one of its longitudinal ends, and the fourthtransducer beam side portion 512 is disposed generally perpendicular tothe side portion 502 b of the central body portion 502 and to thirdtransducer beam side portion 510. The third transducer beam side portion510 is connected to the second transducer beam side portion 508 on oneof its longitudinal ends, and the fourth transducer beam side portion512 on the other one of its longitudinal ends, and the third transducerbeam side portion 510 is disposed generally perpendicular to each of thesecond and fourth transducer beam side portions 508, 512. Also, as shownin FIG. 21, it can be seen that the top surface of the third transducerbeam side portion 510 and the top surface of the sixth transducer beamside portion 516 each comprises a central standoff portion 518. Thecentral standoff portions 518 each comprise spaced apart mountingapertures 522 (e.g., two spaced apart apertures 522) disposedtherethrough for accommodating fasteners (e.g., screws) that attach theload transducer 500 to another object, such as a robotic arm, etc.

As best shown in the perspective view of FIG. 21, the illustrated loadcells are located on the transducer beam side portions 506, 508, 510,512, 514, 516. In the illustrated embodiment, each load cell comprisesone or more strain gages 524, 526, 528. Specifically, in the illustratedembodiment, the first transducer beam side portion 506, the secondtransducer beam side portion 508, the fourth transducer beam sideportion 512, and the fifth transducer beam side portion 514 eachcomprise a strain gage 524 disposed on the top surface thereof that issensitive to the vertical force component (i.e., a F_(Z) strain gage).The third transducer beam side portion 510 and the sixth transducer beamside portion 516 also each comprise a plurality of spaced apart straingages 526 (e.g., two spaced apart strain gages 526) disposed on a sidesurface thereof that is sensitive to a first shear force component(i.e., a F_(X) strain gage). Also, in the illustrated embodiment, thefirst transducer beam side portion 506, the second transducer beam sideportion 508, the fourth transducer beam side portion 512, and the fifthtransducer beam side portion 514 each comprises a strain gage 528disposed on an outer side surface thereof that is sensitive to a secondshear force component (i.e., a F_(Y) strain gage).

FIG. 22 illustrates a load transducer 600 according to an eighthexemplary embodiment of the present invention. With reference to thisfigure, it can be seen that, in some respects, the eighth exemplaryembodiment is similar to that of the preceding embodiments. Moreover,some parts are common to all of the embodiments. For the sake ofbrevity, the parts that the eighth embodiment of the load transducer hasin common with the preceding embodiments will only be briefly mentionedbecause these components have already been explained in detail above.

Initially, referring to the perspective view of FIG. 22, it can be seenthat, like the preceding embodiments described above, the loadtransducer 600 generally includes a one-piece compact transducer frame604 with a central body portion 602 and a plurality of transducer beams606, 608, 610, 612, 614, 616 connected thereto. Although, the transducerbeams 606, 608, 610, 612, 614, 616 are arranged in a differentconfiguration than that which was described for the precedingembodiments.

With reference again to FIG. 22, it can be seen that the illustratedcentral body portion 602 is generally in the form of square band-shapedelement with a central opening 630 disposed therethrough. In FIG. 22, itcan be seen that the body portion 602 comprises a first pair of opposedside portions 602 a, 602 c and a second pair of opposed side portions602 b, 602 d. The side portion 602 a is disposed generally parallel tothe side portion 602 c, while the side portion 602 b is disposedgenerally parallel to the side portion 602 d. Each of the side surfacesof the side portions 602 a, 602 b, 602 c, 602 d is disposed generallyperpendicular to the planar top and bottom surfaces thereof. Also, eachof the first pair of opposed side portions 602 a, 602 c is disposedgenerally perpendicular to each of the second pair of opposed sidesportions 602 b, 602 d. In addition, as shown in FIG. 22, each of theopposed side portions 602 b, 602 d is connected to a respective set oftransducer beams 606, 608, 610 and 612, 614, 616. In the illustratedembodiment, it can be seen that each of the opposed side portions 602 a,602 c comprises a plurality of apertures 632 (e.g., two apertures 632)disposed therethrough for accommodating fasteners (e.g., screws) thatattach the load transducer 600 to another object, such as a robotic arm,etc.

As shown in FIG. 22, the first set of illustrated transducer beams 606,608, 610 of the transducer frame 604 is arranged in a generally T-shapedconfiguration on a first side of the central body portion 602. A firstside aperture 634 is formed between the side portion 602 d of thecentral body portion 602 and the first set of transducer beam sideportions 606, 608, 610. Referring again to FIG. 22, it can be seen thatthe first transducer beam 606 is connected to the side portion 602 d ofthe central body portion 602 by means of two spaced apart connectingtransducer beams 608, 610. Specifically, the second transducer beam 608is connected to an inner side of the first transducer beam 606 on one ofits longitudinal ends, and the side portion 602 d of the central bodyportion 602 on the other one of its longitudinal ends, and the secondtransducer beam 608 is disposed generally perpendicular to the sideportion 602 d of the central body portion 602 and to first transducerbeam 606. Similarly, the third transducer beam 610 is connected to theinner side of the first transducer beam 606 on one of its longitudinalends, and the side portion 602 d of the central body portion 602 on theother one of its longitudinal ends, and the third transducer beam 610 isdisposed generally perpendicular to the side portion 602 d of thecentral body portion 602 and to first transducer beam 606. Turning againto FIG. 22, it can be seen that the second set of transducer beams 612,614, 616 of the transducer frame 604 is arranged in a generally T-shapedconfiguration on a second side of the central body portion 602, which isopposite to the first side of the central body portion 602. A secondside aperture 634 is formed between the side portion 602 b of thecentral body portion 602 and the second set of transducer beam sideportions 612, 614, 616. In FIG. 22, similar to the first transducer beam606, it can be seen that the fourth transducer beam 612 is connected tothe side portion 602 b of the central body portion 602 by means of twospaced apart connecting transducer beams 614, 616. Specifically, thefifth transducer beam 614 is connected to an inner side of the fourthtransducer beam 612 on one of its longitudinal ends, and the sideportion 602 b of the central body portion 602 on the other one of itslongitudinal ends, and the fifth transducer beam 614 is disposedgenerally perpendicular to the side portion 602 b of the central bodyportion 602 and to fourth transducer beam 612. Similarly, the sixthtransducer beam 616 is connected to the inner side of the fourthtransducer beam 612 on one of its longitudinal ends, and the sideportion 602 b of the central body portion 602 on the other one of itslongitudinal ends, and the sixth transducer beam 616 is disposedgenerally perpendicular to the side portion 602 b of the central bodyportion 602 and to fourth transducer beam 612. Also, as shown in FIG.22, it can be seen that the bottom surface of the first transducer beam606 and the bottom surface of the fourth transducer beam 612 eachcomprises a central standoff portion 620. In addition, it can be seenthat the opposed longitudinal ends of the first transducer beam 606 andthe fourth transducer beam 612 are each provided with raised standoffportions 618. Each raised standoff portion 618 is provided with amounting aperture 622 disposed therethrough for accommodating arespective fastener (e.g., a screw) that attaches the load transducer600 to another object, such as a robotic arm, etc.

As best shown in the perspective view of FIG. 22, the illustrated loadcells are located on the transducer beams 606, 608, 610, 612, 614, 616.In the illustrated embodiment, each load cell comprises one or morestrain gages 624, 626, 628. Specifically, in the illustrated embodiment,the first transducer beam 606 and the fourth transducer beam 612 eachcomprise a pair of spaced apart strain gages 624 disposed on the topsurfaces thereof that are sensitive to the vertical force component(i.e., F_(Z) strain gages). In FIG. 22, it can be seen that each of thestrain gages 624 is disposed near the raised standoff portions 618 atthe opposed ends of the beams 606, 612. Also, in the illustratedembodiment, the second transducer beam 608, the third transducer beam610, the fifth transducer beam 614, and the sixth transducer beam 616each comprise a strain gage 626 disposed on an outer side surfacethereof that is sensitive to a first shear force component (i.e., aF_(X) strain gage). The first transducer beam 606 and the fourthtransducer beam 612 also each comprise a plurality of spaced apartstrain gages 628 (e.g., two spaced apart strain gages 628) disposed onan outer side surface thereof that is sensitive to a second shear forcecomponent (i.e., a F_(Y) strain gage).

FIG. 23 illustrates a load transducer 700 according to a ninth exemplaryembodiment of the present invention. With reference to this figure, itcan be seen that, in some respects, the ninth exemplary embodiment issimilar to that of the eighth embodiment. Moreover, some parts arecommon to all of the embodiments. For the sake of brevity, the partsthat the ninth embodiment of the load transducer has in common with theeighth embodiment will only be briefly mentioned because thesecomponents have already been explained in detail above.

Initially, referring to the perspective view of FIG. 23, it can be seenthat, like the eighth embodiment described above, the load transducer700 generally includes a one-piece compact transducer frame 704 with acentral body portion 702 and a plurality of transducer beams 706, 708,710, 712, 714, 716 connected thereto. Although, each of connectingtransducer beams 708, 710, and each of connecting transducer beams 714,716, are spaced considerably further apart from one another as comparedto the connecting transducer beams 608, 610, 614, 616 of the loadtransducer 600 such that the connecting beams 708, 710, 714, 716 aregenerally axially aligned with the side portions 702 a, 702 c of thecentral body portion 702.

With reference again to FIG. 23, it can be seen that the illustratedcentral body portion 702 is generally in the form of square band-shapedelement with a central opening 730 disposed therethrough. In FIG. 23, itcan be seen that the body portion 702 comprises a first pair of opposedside portions 702 a, 702 c and a second pair of opposed side portions702 b, 702 d. The side portion 702 a is disposed generally parallel tothe side portion 702 c, while the side portion 702 b is disposedgenerally parallel to the side portion 702 d. Each of the side surfacesof the side portions 702 a, 702 b, 702 c, 702 d is disposed generallyperpendicular to the planar top and bottom surfaces thereof. Also, eachof the first pair of opposed side portions 702 a, 702 c is disposedgenerally perpendicular to each of the second pair of opposed sidesportions 702 b, 702 d. In addition, as shown in FIG. 23, each of theopposed side portions 702 b, 702 d is connected to a respective set oftransducer beams 706, 708, 710 and 712, 714, 716. In the illustratedembodiment, it can be seen that each of the opposed side portions 702 a,702 c comprises a plurality of apertures 732 (e.g., two apertures 732)disposed therethrough for accommodating fasteners (e.g., screws) thatattach the load transducer 700 to another object, such as a robotic arm,etc. Also, as depicted in the FIG. 23, the central body portion 702comprises a raised bottom portion or bottom standoff portion 720 forspacing the transducer beams 706, 708, 710, 712, 714, 716 apart from anobject (e.g., robotic arm) to which the load transducer 700 is attachedso that forces and/or moments are capable of being accurately measuredby the load transducer 700.

As shown in FIG. 23, the first set of illustrated transducer beams 706,708, 710 of the transducer frame 704 is arranged in a generally T-shapedconfiguration on a first side of the central body portion 702 (with thewide base of the T-shaped arrangement being formed by the connectingbeam transducers 708, 710). A first side aperture 734 is formed betweenthe side portion 702 d of the central body portion 702 and the first setof transducer beam side portions 706, 708, 710. Referring again to FIG.23, it can be seen that the first transducer beam 706 is connected tothe side portion 702 d of the central body portion 702 by means of twospaced apart connecting transducer beams 708, 710. Specifically, thesecond transducer beam 708 is connected to an inner side of the firsttransducer beam 706 on one of its longitudinal ends, and the sideportion 702 d of the central body portion 702 on the other one of itslongitudinal ends, and the second transducer beam 708 is disposedgenerally perpendicular to the side portion 702 d of the central bodyportion 702 and to first transducer beam 706. Similarly, the thirdtransducer beam 710 is connected to the inner side of the firsttransducer beam 706 on one of its longitudinal ends, and the sideportion 702 d of the central body portion 702 on the other one of itslongitudinal ends, and the third transducer beam 710 is disposedgenerally perpendicular to the side portion 702 d of the central bodyportion 702 and to first transducer beam 706. Turning again to FIG. 23,it can be seen that the second set of transducer beams 712, 714, 716 ofthe transducer frame 704 is arranged in a generally T-shapedconfiguration on a second side of the central body portion 702, which isopposite to the first side of the central body portion 702 (with thewide base of the T-shaped arrangement being formed by the connectingbeam transducers 714, 716). A second side aperture 734 is formed betweenthe side portion 702 b of the central body portion 702 and the secondset of transducer beam side portions 712, 714, 716. In FIG. 23, similarto the first transducer beam 706, it can be seen that the fourthtransducer beam 712 is connected to the side portion 702 b of thecentral body portion 702 by means of two spaced apart connectingtransducer beams 714, 716. Specifically, the fifth transducer beam 714is connected to an inner side of the fourth transducer beam 712 on oneof its longitudinal ends, and the side portion 702 b of the central bodyportion 702 on the other one of its longitudinal ends, and the fifthtransducer beam 714 is disposed generally perpendicular to the sideportion 702 b of the central body portion 702 and to fourth transducerbeam 712. Similarly, the sixth transducer beam 716 is connected to theinner side of the fourth transducer beam 712 on one of its longitudinalends, and the side portion 702 b of the central body portion 702 on theother one of its longitudinal ends, and the sixth transducer beam 716 isdisposed generally perpendicular to the side portion 702 b of thecentral body portion 702 and to fourth transducer beam 712. Also, inFIG. 23, it can be seen that the opposed longitudinal ends of the firsttransducer beam 706 and the fourth transducer beam 712 are each providedwith raised standoff portions 718. Each raised standoff portion 718 isprovided with a mounting aperture 722 disposed therethrough foraccommodating a respective fastener (e.g., a screw) that attaches theload transducer 700 to another object, such as a robotic arm, etc.

As best shown in the perspective view of FIG. 23, the illustrated loadcells are located on the transducer beams 706, 708, 710, 712, 714, 716.In the illustrated embodiment, each load cell comprises one or morestrain gages 724, 726, 728. Specifically, in the illustrated embodiment,the first transducer beam 706 and the fourth transducer beam 712 eachcomprise a pair of spaced apart strain gages 724 disposed on the topsurfaces thereof that are sensitive to the vertical force component(i.e., F_(Z) strain gages). In FIG. 23, it can be seen that each of thestrain gages 724 is disposed near the raised standoff portions 718 atthe opposed ends of the beams 706, 712. Also, in the illustratedembodiment, the second transducer beam 708, the third transducer beam710, the fifth transducer beam 714, and the sixth transducer beam 716each comprise a strain gage 726 disposed on an outer side surfacethereof that is sensitive to a first shear force component (i.e., aF_(X) strain gage). The first transducer beam 706 and the fourthtransducer beam 712 also each comprise a plurality of spaced apartstrain gages 728 (e.g., two spaced apart strain gages 728) disposed onan outer side surface thereof that is sensitive to a second shear forcecomponent (i.e., a F_(Y) strain gage).

FIG. 24 illustrates a load transducer 800 according to a tenth exemplaryembodiment of the present invention. With reference to this figure, itcan be seen that, in some respects, the tenth exemplary embodiment issimilar to that of the preceding embodiments. Moreover, some parts arecommon to all of the embodiments. For the sake of brevity, the partsthat the tenth embodiment of the load transducer has in common with thepreceding embodiments will only be briefly mentioned because thesecomponents have already been explained in detail above.

Initially, referring to the perspective view of FIG. 24, it can be seenthat the load transducer 800 generally includes a one-piece compacttransducer frame 804 with a central body portion 802 and a plurality ofL-shaped transducer beams 806, 808, 810, 812 connected thereto. As shownin FIG. 24, each of the L-shaped transducer beams 806, 808, 810, 812 isgenerally disposed at a respective corner of the central body portion802.

With reference again to FIG. 24, it can be seen that the illustratedcentral body portion 802 is generally in the form of square band-shapedelement with a central opening 826 disposed therethrough. In FIG. 24, itcan be seen that the body portion 802 comprises a first pair of opposedside portions 802 a, 802 c and a second pair of opposed side portions802 b, 802 d. The side portion 802 a is disposed generally parallel tothe side portion 802 c, while the side portion 802 b is disposedgenerally parallel to the side portion 802 d. Each of the side surfacesof the side portions 802 a, 802 b, 802 c, 802 d is disposed generallyperpendicular to the planar top and bottom surfaces thereof. Also, eachof the first pair of opposed side portions 802 a, 802 c is disposedgenerally perpendicular to each of the second pair of opposed sidesportions 802 b, 802 d. In addition, as shown in FIG. 24, each of thecorners of the central body portion 802 is connected to a respectiveL-shaped transducer beam 806, 808, 810, 812. In the illustratedembodiment, it can be seen that each of the opposed side portions 802 a,802 c comprises a plurality of apertures 828 (e.g., two apertures 828)disposed therethrough for accommodating fasteners (e.g., screws) thatattach the load transducer 800 to another object, such as a robotic arm,etc. Also, as depicted in the FIG. 24, the central body portion 802comprises a raised bottom portion or bottom standoff portion 816 forspacing the L-shaped transducer beams 806, 808, 810, 812 apart from anobject (e.g., robotic arm) to which the load transducer 800 is attachedso that forces and/or moments are capable of being accurately measuredby the load transducer 800.

As shown in FIG. 24, the first generally L-shaped transducer beam 806comprises a first beam portion 806 a and a second beam portion 806 b,wherein the first beam portion 806 a is disposed generally perpendicularto the second beam portion 806 b. Similarly, the second generallyL-shaped transducer beam 808 comprises a first beam portion 808 a and asecond beam portion 808 b, wherein the first beam portion 808 a isdisposed generally perpendicular to the second beam portion 808 b. Also,it can be seen in FIG. 24 that the first beam portion 806 a of the firstgenerally L-shaped transducer beam 806 and the first beam portion 808 aof the second generally L-shaped transducer beam 808 are both generallyaxially aligned with the side portion 802 a of the central body portion802 (i.e., the longitudinal axes of the beam portions 806 a, 808 a aregenerally aligned with the longitudinal axis of the side portion 802 a).With reference again to FIG. 24, the third generally L-shaped transducerbeam 810 comprises a first beam portion 810 a and a second beam portion810 b, wherein the first beam portion 810 a is disposed generallyperpendicular to the second beam portion 810 b. Similarly, the fourthgenerally L-shaped transducer beam 812 comprises a first beam portion812 a and a second beam portion 812 b, wherein the first beam portion812 a is disposed generally perpendicular to the second beam portion 812b. Also, it can be seen in FIG. 24 that the first beam portion 810 a ofthe third generally L-shaped transducer beam 810 and the first beamportion 812 a of the fourth generally L-shaped transducer beam 812 areboth generally axially aligned with the side portion 802 c of thecentral body portion 802 (i.e., the longitudinal axes of the beamportions 810 a, 812 a are generally aligned with the longitudinal axisof the side portion 802 c). Also, in FIG. 24, it can be seen that thefree ends of the second beam portions 806 b, 808 b, 810 b, 812 b of theL-shaped transducer beams 806, 808, 810, 812 are each provided withraised standoff portions 814. Each raised standoff portion 814 isprovided with a mounting aperture 818 disposed therethrough foraccommodating a respective fastener (e.g., a screw) that attaches theload transducer 800 to another object, such as a robotic arm, etc.

As best shown in the perspective view of FIG. 24, the illustrated loadcells are located on the L-shaped transducer beams 806, 808, 810, 812.In the illustrated embodiment, each load cell comprises one or morestrain gages 820, 822, 824. Specifically, in the illustrated embodiment,the second beam portions 806 b, 808 b, 810 b, 812 b of the L-shapedtransducer beams 806, 808, 810, 812 are each provided with a strain gage820 disposed on the top surface thereof that is sensitive to thevertical force component (i.e., an F_(Z) strain gage). In FIG. 24, itcan be seen that each of the strain gages 820 is disposed near theraised standoff portions 818 of the second beam portions 806 b, 808 b,810 b, 812 b. Also, in the illustrated embodiment, the second beamportions 806 b, 808 b, 810 b, 812 b of the L-shaped transducer beams806, 808, 810, 812 each comprise a strain gage 822 disposed on an outerside surface thereof that is sensitive to a first shear force component(i.e., a F_(X) strain gage). The first beam portions 806 a, 808 a, 810a, 812 a of the L-shaped transducer beams 806, 808, 810, 812 eachcomprise a strain gage 824 disposed on an outer side surface thereofthat is sensitive to a second shear force component (i.e., a F_(Y)strain gage).

In the illustrated embodiments of the present invention, the transducerbeams do not extend from a top or upper surface of the central bodyportion. As such, there is no gap formed between the top or uppersurface of the central body portion and a bottom or lower surface of oneor more of the transducer beams. Rather, in the exemplary embodimentscomprising a central body portion, the transducer beams extend outwardlyfrom a side or lateral surface of the central body portion so as tominimize the overall height of the transducer profile (i.e., because thetransducer beams are not required to be disposed above the central bodyportion). Also, in the illustrated embodiments discussed above, thetransducer beams are not in the form of generally linear beams, and arenot in the form of generally linear beams with generally symmetrical endportions. Rather, the transducer beams of the exemplary embodimentsgenerally either emanate from a central body portion and have only onecantilevered end or are arranged in a continuous band-likeconfiguration. In addition, it can be seen that, except for the top andbottom standoff portions on either the transducer beams or the centralbody portions, the top and bottom surfaces of the transducer beams ofthe exemplary embodiments are generally co-planar with the respectivetop and bottom surfaces of the central body portion. Similarly, in theexemplary embodiments having a band-like configuration of transducerbeams, the top surfaces of each of the looped transducer beams aregenerally co-planar with one another, while the bottom surfaces of eachof the looped transducer beams are also generally co-planar with oneanother.

FIGS. 26-29 illustrate a load transducer 900 according to an eleventhexemplary embodiment of the present invention. Referring initially tothe top perspective view of FIG. 26, it can be seen that the loadtransducer 900 generally includes a one-piece compact transducer frame902 having a plurality of transducer beam portions 904, 906, 908, 910,912 connected to one another in succession. As best shown in theperspective views of FIGS. 26 and 29, the plurality of transducer beamportions 904, 906, 908, 910, 912 are arranged in a circumscribingpattern whereby a central one of the plurality of transducer beamportions (i.e., transducer beam portion 904) is at least partiallycircumscribed by one or more outer ones of the plurality of beamportions (i.e., transducer beam portions 906, 908, 910, 912). In otherwords, the plurality of transducer beam portions 904, 906, 908, 910, 912forming the load transducer 900 are arranged in a looped configurationwhereby a central one of the plurality of beam portions (i.e.,transducer beam portion 904) emanates from a generally central locationwithin a footprint of the load transducer 900 and outer ones of theplurality of beam portions (i.e., transducer beam portions 906, 908,910, 912) are wrapped around the central one of the plurality of beamportions. As best illustrated in the perspective views of FIGS. 26 and29, each of the beam portions 908, 910, 912 comprise one or more loadcells or transducer elements for measuring forces and/or moments.

As shown in FIGS. 26-29, the illustrated transducer beam portions 904,906, 908, 910, 912 are arranged in a generally spiral-shaped patternthat emanates from the centrally located transducer beam portion 904.The pattern in which the transducer beam portions 904, 906, 908, 910,912 are arranged is also generally G-shaped (refer to FIGS. 26 and 29).With particular reference to the perspective views of FIGS. 26 and 29,it can be seen that the transducer beam portions 904, 906, 908, 910, 912of the load transducer 900 are arranged in such a configuration thateach of the successive transducer beam portions are disposedsubstantially perpendicular to the immediately preceding transducer beamportion. For example, referring to FIG. 26, the first transducer beamportion 904 is disposed at the approximate center of the transducerfootprint, the second transducer beam portion 906 is connected to thefirst transducer beam portion 904 and is disposed substantiallyperpendicular thereto, the third transducer beam portion 908 isconnected to the second transducer beam portion 906 and is disposedsubstantially perpendicular thereto, the fourth transducer beam portion910 is connected to the third transducer beam portion 908 and isdisposed substantially perpendicular thereto, and the fifth transducerbeam portion 912 is connected to the fourth transducer beam portion 910and is disposed substantially perpendicular thereto. In FIGS. 26 and 29,it can be seen that the transducer beam portions 904, 906, 908, 910, 912of the load transducer 900 are spaced apart from one another by agenerally U-shaped, central gap 942, which is bounded by each of thetransducer beam portions 904, 906, 908, 910, 912. In particular, thefirst transducer beam portion 904 and the third transducer beam portion908, which are disposed generally parallel to one another, are laterallyspaced apart by the gap 942. Similarly, the second transducer beamportion 906 and the fourth transducer beam portion 910, which aredisposed generally parallel to one another, are laterally spaced apartby the gap 942. Also, the first transducer beam portion 904 and thefifth transducer beam portion 912, which are disposed generally parallelto one another, are laterally spaced apart by the gap 942. The thirdtransducer beam portion 908 and the fifth transducer beam portion 912,which are disposed generally parallel to one another, are laterallyspaced apart by the gap 942 and a segment of the first transducer beamportion 904.

Referring again to the top perspective view of FIG. 26, it can be seenthat the first and second transducer beam portions 904, 906 of the loadtransducer 900 together comprise an L-shaped raised portion or standoffportion 920 with mounting apertures 924 (e.g., three apertures 924)disposed therethrough for accommodating fasteners (e.g., screws) thatattach the load transducer 900 to another object, such as a platecomponent of a force plate or force measurement assembly. The mountingapertures 924 pass completely through the first and second transducerbeam portions 904, 906, and are provided with respective bottom boreportions 924 a of increased diameter (see FIG. 29) in order toaccommodate fasteners (e.g., screws) with fillister heads that have alarger outer diameter than the threaded portions of the fasteners. Inaddition, with reference again to FIG. 26, it can be seen that theelevated L-shaped top surface of the first and second transducer beamportions 904, 906 is provided with pin locating bores 926 (e.g., twobores 926) formed therein for receiving locating pins that ensure theproper positioning of the load transducer 900 on the object to which itis mounted, such as a plate component of a force plate or forcemeasurement assembly. The locating pins are received within the pinlocating bores 926 on the load transducer 900 and within correspondingpin locating bores provided on the object (e.g., the force plate orforce measurement assembly). As depicted in the bottom perspective viewof FIG. 29, the fifth transducer beam portion 912 of the load transducer900 comprises a generally rectangular or square raised portion orstandoff portion 922 with a mounting aperture 928 (e.g., a singleaperture 928) disposed therethrough for accommodating a fastener (e.g.,a screw) that attaches the load transducer 900 to another object, suchas a mounting foot of a force plate or force measurement assembly.Advantageously, the standoff portions 920, 922 on the top and bottom ofthe load transducer 900 elevate the transducer beam portions 904, 906,908, 910, 912 above the object(s) to which the load transducer 900 isattached so that forces and/or moments are capable of being accuratelymeasured by the load transducer 900. In one or more embodiments, thestructural components to which the load transducer 900 is mounted areconnected only to the top standoff portion 920 and the bottom standoff922 so as to ensure that the total load applied to the load transducer900 is transmitted through the transducer beam portions 904, 906, 908,910, 912.

In the illustrative embodiment, the third, fourth, and fifth transducerbeam portions 908, 910, 912 have a top surface that is disposed at afirst elevation relative to a bottom surface of the load transducer 900,whereas the L-shaped raised portion 920 of the first and secondtransducer beam portions 904, 906 has a top surface that is disposed ata second elevation relative to the bottom surface of the load transducer900. As best shown in FIGS. 26-28, the second elevation is greater thanthe first elevation such that a recessed area is created by thedifference in elevation between the second elevation and the firstelevation. In the illustrated embodiment, the recessed area is used toaccommodate electrical components of the transducer load cells (e.g.,strain gages 934, 936 a, 938 a).

In the illustrative embodiment of FIGS. 26-29, each of the transducerbeam portions 908, 910, 912 is provided with a respective aperture 914,916, 918 disposed therethrough. In particular, the third transducer beamportion 908 is provided with a generally rectangular aperture 914disposed vertically through the beam portion. Similarly, the fourthtransducer beam portion 910 is provided with a generally rectangularaperture 916 disposed vertically through the beam portion. The fifthtransducer beam portion 912 is provided with a generally rectangularaperture 918 disposed horizontally through the beam portion. Theapertures 914, 916, 918, which are disposed through the respectivetransducer beam portions 908, 910, 912, significantly increase thesensitivity of the load transducer 900 when a load is applied thereto byreducing the cross-sectional area of the transducer beam portions 908,910, 912 at the locations of the apertures 914, 916, 918.

As best shown in the perspective views of FIGS. 26 and 29, theillustrated load cells are located on the transducer beam portions 908,910, 912. In the illustrated embodiment, each load cell comprises one ormore strain gages 930, 932, 934, 936 a, 936 b, 938 a, 938 b, 940 a, and940 b. Specifically, in the illustrated embodiment, the third transducerbeam portion 908 of the load transducer 900 comprises a strain gage 932disposed on a side surface thereof that is sensitive to a first shearforce component (i.e., a F_(Y) strain gage) and substantially centeredon the aperture 914. The third transducer beam portion 908 alsocomprises a set of strain gages 938 a, 938 b that are sensitive to afirst moment component (i.e., a M_(Y) strain gages). The strain gages938 a, 938 b are disposed on opposed side surfaces (e.g., top and bottomsurfaces) of the third transducer beam portion 908, and aresubstantially vertically aligned with one another. Turning again toFIGS. 26 and 29, in the illustrated embodiment, the fourth transducerbeam portion 910 of the load transducer 900 comprises a strain gage 930disposed on a side surface thereof that is sensitive to a second shearforce component (i.e., a F_(X) strain gage) and substantially centeredon the aperture 916. The fourth transducer beam portion 910 alsocomprises a set of strain gages 936 a, 936 b that are sensitive to asecond moment component (i.e., a M_(X) strain gages). Like the straingages 938 a, 938 b, the strain gages 936 a, 936 b are disposed onopposed side surfaces (e.g., top and bottom surfaces) of the fourthtransducer beam portion 910, and are substantially vertically alignedwith one another. With reference again to FIGS. 26 and 29, in theillustrated embodiment, the fifth transducer beam portion 912 of theload transducer 900 comprises a strain gage 934 disposed on the topsurface thereof that is sensitive to a vertical force component (i.e., aF_(Z) strain gage) and substantially centered on the aperture 918. Thefifth transducer beam portion 912 also comprises a set of strain gages940 a, 940 b that are sensitive to a third moment component (i.e., aM_(Z) strain gages). Like the strain gages 936 a, 936 b and 938 a, 938b, the strain gages 940 a, 940 b are disposed on opposed side surfaces(e.g., first and second lateral surfaces) of the fifth transducer beamportion 912, and are substantially horizontally aligned with oneanother. In the illustrated embodiment, the first shear force componentis generally perpendicular to the second shear force component, and eachof the first and second shear force components are generallyperpendicular to the vertical force component.

In the illustrated embodiment, the strain gages 930, 932, 934 aredisposed on respective outer surfaces of the transducer beam portions910, 908, 912. The outer surfaces of the transducer beam portions 910,908, 912 on which the strain gages 930, 932, 934 are disposed aregenerally opposite to the inner surfaces of the respective apertures916, 914, 918.

As best shown in FIGS. 26 and 29, the illustrated load cells are mountedon top, bottom, or side surfaces of the transducer beam portions 908,910, 912 between the standoff portions 920, 922 of the load transducer900. Alternatively, the strain gages 932, 930 can be mounted to theinner side surfaces of the respective third and fourth transducer beamportions 908, 910, rather than to the outer side surfaces of therespective third and fourth transducer beam portions 908, 910 asillustrated in FIGS. 26 and 29. Similarly, the strain gage 934 can bemounted to the bottom surface of the fifth transducer beam portion 912,rather than to the top of the transducer beam portion 912 as illustratedin FIG. 26. In general, the strain gages 930, 932, 934 are mounted tosurfaces generally normal to the direction of applied vertical and/orshear forces (i.e., F_(X), F_(Y), F_(Z)). It is also noted thatalternatively, strain gages 930 can be mounted at both opposed sidesurfaces of fourth transducer beam portion 910 and/or strain gages 932can be mounted at both opposed side surfaces of the third transducerbeam portion 908. Similarly, strain gages 934 can be mounted at both thetop surface and the bottom surface of the fifth transducer beam portion912. These strain gages 930, 932, 934 measure force either by bendingmoment or difference of bending moments at two cross sections. As forceis applied to the ends of the load transducer 900, the transducer beamportions bend. This bending either stretches or compresses the straingages 930, 932, 934, which in turn changes the resistance of theelectrical current passing therethrough. The amount of change in theelectrical voltage or current is proportional to the magnitude of theapplied force, as applied to the L-shaped standoff portion 920.

In the illustrated embodiment, each of the strain gages 930, 932, 934comprises a full-bridge strain gage configuration (i.e., four (4) activestrain gage elements wired in a Wheatstone bridge configuration), whileeach of the strain gages 936 a, 936 b, 938 a, 938 b, 940 a, and 940 bcomprises a half-bridge strain gage configuration (i.e., two (2) activestrain gage elements). Also, in the illustrative embodiment, the pair ofstrain gages 936 a, 936 b are wired together in one Wheatstone bridgeconfiguration (i.e., with a total of four (4) active strain gageelements), the pair of strain gages 938 a, 938 b are wired together inanother Wheatstone bridge configuration (i.e., with a total of four (4)active strain gage elements), and the pair of strain gages 940 a, 940 bare wired together in yet another Wheatstone bridge configuration (i.e.,with a total of four (4) active strain gage elements).

FIGS. 30-33 illustrate a load transducer 1000 according to a twelfthexemplary embodiment of the present invention. With reference to thesefigures, it can be seen that the load transducer 1000 is similar in manyrespects to the load transducer 900 of the eleventh embodiment describedabove. However, unlike the aforedescribed load transducer 900, the loadtransducer 1000 only measures the force components of a load (i.e.,F_(X), F_(Y), F_(Z)), rather than both the force and moment componentsof a load as explained above with regard to the load transducer 1000.

Initially, referring to the top perspective view of FIG. 30, it can beseen that the load transducer 1000 generally includes a one-piececompact transducer frame 1002 having a plurality of transducer beamportions 1004, 1006, 1008, 1010, 1012 connected to one another insuccession. As best shown in the perspective views of FIGS. 30 and 33,the plurality of transducer beam portions 1004, 1006, 1008, 1010, 1012are arranged in a circumscribing pattern whereby a central one of theplurality of transducer beam portions (i.e., transducer beam portion1004) is at least partially circumscribed by one or more outer ones ofthe plurality of beam portions (i.e., transducer beam portions 1006,1008, 1010, 1012). In other words, the plurality of transducer beamportions 1004, 1006, 1008, 1010, 1012 forming the load transducer 1000are arranged in a looped configuration whereby a central one of theplurality of beam portions (i.e., transducer beam portion 1004) emanatesfrom a generally central location within a footprint of the loadtransducer 1000 and outer ones of the plurality of beam portions (i.e.,transducer beam portions 1006, 1008, 1010, 1012) are wrapped around thecentral one of the plurality of beam portions. As best illustrated inthe perspective views of FIGS. 30 and 33, each of the beam portions1008, 1010, 1012 comprise one or more load cells or transducer elementsfor measuring the various components of an applied force.

As shown in FIGS. 30-33, the illustrated transducer beam portions 1004,1006, 1008, 1010, 1012 are arranged in a generally spiral-shaped patternthat emanates from the centrally located transducer beam portion 1004.The pattern in which the transducer beam portions 1004, 1006, 1008,1010, 1012 are arranged is also generally G-shaped (refer to FIGS. 30and 33). With particular reference to the perspective views of FIGS. 30and 33, it can be seen that the transducer beam portions 1004, 1006,1008, 1010, 1012 of the load transducer 1000 are arranged in such aconfiguration that each of the successive transducer beam portions aredisposed substantially perpendicular to the immediately precedingtransducer beam portion. For example, referring to FIG. 30, the firsttransducer beam portion 1004 is disposed at the approximate center ofthe transducer footprint, the second transducer beam portion 1006 isconnected to the first transducer beam portion 1004 and is disposedsubstantially perpendicular thereto, the third transducer beam portion1008 is connected to the second transducer beam portion 1006 and isdisposed substantially perpendicular thereto, the fourth transducer beamportion 1010 is connected to the third transducer beam portion 1008 andis disposed substantially perpendicular thereto, and the fifthtransducer beam portion 1012 is connected to the fourth transducer beamportion 1010 and is disposed substantially perpendicular thereto. InFIGS. 30 and 33, it can be seen that the transducer beam portions 1004,1006, 1008, 1010, 1012 of the load transducer 1000 are spaced apart fromone another by a generally U-shaped, central gap 1032, which is boundedby each of the transducer beam portions 1004, 1006, 1008, 1010, 1012. Inparticular, the first transducer beam portion 1004 and the thirdtransducer beam portion 1008, which are disposed generally parallel toone another, are laterally spaced apart by the gap 1032. Similarly, thesecond transducer beam portion 1006 and the fourth transducer beamportion 1010, which are disposed generally parallel to one another, arelaterally spaced apart by the gap 1032. Also, the first transducer beamportion 1004 and the fifth transducer beam portion 1012, which aredisposed generally parallel to one another, are laterally spaced apartby the gap 1032. The third transducer beam portion 1008 and the fifthtransducer beam portion 1012, which are disposed generally parallel toone another, are laterally spaced apart by the gap 1032 and a segment ofthe first transducer beam portion 1004.

Referring again to the top perspective view of FIG. 30, it can be seenthat the first and second transducer beam portions 1004, 1006 of theload transducer 1000 comprise an L-shaped arrangement of mountingapertures 1020 (e.g., three (3) apertures 1020) disposed therethroughfor accommodating fasteners (e.g., screws) that attach the loadtransducer 1000 to another object, such as a plate component of a forceplate or force measurement assembly. The mounting apertures 1020 passcompletely through the first and second transducer beam portions 1004,1006, and are provided with respective bottom bore portions 1020 a ofincreased diameter (see FIG. 33) in order to accommodate fasteners(e.g., screws) with fillister heads that have a larger outer diameterthan the threaded portions of the fasteners. In addition, with referenceagain to FIG. 30, it can be seen that the L-shaped portion of the loadtransducer 1000 that is formed by the first and second transducer beamportions 1004, 1006 is provided with pin locating bores 1022 (e.g., two(2) bores 1022) formed therein for receiving locating pins that ensurethe proper positioning of the load transducer 1000 on the object towhich it is mounted, such as a plate component of a force plate or forcemeasurement assembly. The locating pins are received within the pinlocating bores 1022 on the load transducer 1000 and within correspondingpin locating apertures provided on the object (e.g., the force plate orforce measurement assembly). As depicted in the perspective views ofFIGS. 30 and 33, the fifth transducer beam portion 1012 of the loadtransducer 1000 comprises a mounting aperture 1024 (e.g., a singleaperture 1024 proximate to the free end thereof) disposed therethroughfor accommodating a fastener (e.g., a screw) that attaches the loadtransducer 1000 to another object, such as a mounting foot of a forceplate or force measurement assembly. In one or more embodiments, theload transducer 1000 is connected to one or more objects in such amanner that the total load applied to the load transducer 1000 istransmitted through the transducer beam portions 1004, 1006, 1008, 1010,1012.

In the illustrative embodiment of FIGS. 30-33, each of the transducerbeam portions 1008, 1010, 1012 is provided with a respective aperture1014, 1016, 1018 disposed therethrough. In particular, the thirdtransducer beam portion 1008 is provided with a generally rectangularaperture 1014 disposed vertically through the beam portion. Similarly,the fourth transducer beam portion 1010 is provided with a generallyrectangular aperture 1016 disposed vertically through the beam portion.The fifth transducer beam portion 1012 is provided with a generallyrectangular aperture 1018 disposed horizontally through the beamportion. The apertures 1014, 1016, 1018, which are disposed through therespective transducer beam portions 1008, 1010, 1012, significantlyincrease the sensitivity of the load transducer 1000 when a load isapplied thereto by reducing the cross-sectional area of the transducerbeam portions 1008, 1010, 1012 at the locations of the apertures 1014,1016, 1018.

As best shown in the perspective views of FIGS. 30 and 33, theillustrated load cells are located on the transducer beam portions 1008,1010, 1012. In the illustrated embodiment, each load cell comprises oneor more strain gages 1026, 1028, and 1030. Specifically, in theillustrated embodiment, the third transducer beam portion 1008 of theload transducer 1000 comprises a strain gage 1028 disposed on a sidesurface thereof that is sensitive to a first shear force component(i.e., a F_(Y) strain gage) and substantially centered on the aperture1014. Turning again to FIGS. 30 and 33, in the illustrated embodiment,the fourth transducer beam portion 1010 of the load transducer 1000comprises a strain gage 1026 disposed on a side surface thereof that issensitive to a second shear force component (i.e., a F_(X) strain gage)and substantially centered on the aperture 1016. With reference again toFIGS. 30 and 33, in the illustrated embodiment, the fifth transducerbeam portion 1012 of the load transducer 1000 comprises a strain gage1030 disposed on the top surface thereof that is sensitive to a verticalforce component (i.e., a F_(Z) strain gage) and substantially centeredon the aperture 1018. In the illustrated embodiment, the first shearforce component is generally perpendicular to the second shear forcecomponent, and each of the first and second shear force components aregenerally perpendicular to the vertical force component.

In the illustrated embodiment, the strain gages 1026, 1028, 1030 aredisposed on respective outer surfaces of the transducer beam portions1010, 1008, 1012. The outer surfaces of the transducer beam portions1010, 1008, 1012 on which the strain gages 1026, 1028, 1030 are disposedare generally opposite to the inner surfaces of the respective apertures1016, 1014, 1018.

As best shown in FIGS. 30 and 33, the illustrated load cells are mountedon top or side surfaces of the transducer beam portions 1008, 1010, 1012between the ends of the load transducer 1000. Alternatively, the straingages 1028, 1026 can be mounted to the inner side surfaces of therespective third and fourth transducer beam portions 1008, 1010, ratherthan to the outer side surfaces of the respective third and fourthtransducer beam portions 1008, 1010 as illustrated in FIGS. 30 and 33.Similarly, the strain gage 1030 can be mounted to the bottom surface ofthe fifth transducer beam portion 1012, rather than to the top of thetransducer beam portion 1012 as illustrated in FIG. 30. In general, thestrain gages 1026, 1028, 1030 are mounted to surfaces generally normalto the direction of applied vertical and/or shear forces (i.e., F_(X),F_(Y), F_(Z)). It is also noted that alternatively, strain gages 1026can be mounted at both opposed side surfaces of fourth transducer beamportion 1010 and/or strain gages 1028 can be mounted at both opposedside surfaces of the third transducer beam portion 1008. Similarly,strain gages 1030 can be mounted at both the top surface and the bottomsurface of the fifth transducer beam portion 1012. These strain gages1026, 1028, 1030 measure force either by bending moment or difference ofbending moments at two cross sections. As force is applied to the endsof the load transducer 1000, the transducer beam portions bend. Thisbending either stretches or compresses the strain gages 1026, 1028,1030, which in turn changes the resistance of the electrical currentpassing therethrough. The amount of change in the electrical voltage orcurrent is proportional to the magnitude of the applied force, asapplied to the load transducer 1000.

In the illustrated embodiment, each of the strain gages 1026, 1028, 1030comprises a full-bridge strain gage configuration (i.e., four (4) activestrain gage elements wired in a Wheatstone bridge configuration) formeasuring the applied vertical and shear forces.

An exemplary embodiment of a force measurement system is illustrated inFIGS. 34-37. In the illustrative embodiment, the force measurementsystem generally comprises a force measurement assembly 1040 (i.e., aforce plate) that is operatively coupled to a data acquisition/dataprocessing device 1060 (i.e., a data acquisition and processing deviceor computing device that is capable of collecting, storing, andprocessing data). The force measurement assembly 1040 illustrated inFIGS. 34-36 is configured to receive a subject thereon, and is capableof measuring the forces and/or moments applied to its measurementsurface by the subject.

As shown in FIG. 34, the data acquisition and processing device 1060(e.g., in the form of a laptop digital computer) generally includes abase portion 1064 with a central processing unit (CPU) disposed thereinfor collecting and processing the data that is received from the forcemeasurement assembly 1040, and a plurality of devices 1066-1070operatively coupled to the central processing unit (CPU) in the baseportion 1064. Preferably, the devices that are operatively coupled tothe central processing unit (CPU) comprise user input devices 1066, 1068in the form of a keyboard 1066 and a touchpad 1068, as well as agraphical user interface in the form of a laptop LCD screen 1070. Whilea laptop type computing system is depicted in the embodiment of FIG. 34,one of ordinary skill in the art will appreciate that another type ofdata acquisition and processing device 1060 can be substituted for thelaptop computing system such as, but not limited to, a palmtop computingdevice (i.e., a PDA) or a desktop type computing system having aplurality of separate, operatively coupled components (e.g., a desktoptype computing system including a main housing with a central processingunit (CPU) and data storage devices, a remote monitor, a remotekeyboard, and a remote mouse).

As illustrated in FIG. 34, force measurement assembly 1040 isoperatively coupled to the data acquisition/data processing device 1060by virtue of an electrical cable 1062. In one embodiment of theinvention, the electrical cable 1062 is used for data transmission, aswell as for providing power to the force measurement assembly 1040.Various types of data transmission cables can be used for cable 1062.For example, the cable 1062 can be a Universal Serial Bus (USB) cable oran Ethernet cable. Preferably, the electrical cable 1062 contains aplurality of electrical wires bundled together, with at least one wirebeing used for power and at least another wire being used fortransmitting data. The bundling of the power and data transmission wiresinto a single electrical cable 1062 advantageously creates a simpler andmore efficient design. In addition, it enhances the safety of thetesting environment when human subjects are being tested on the forcemeasurement assembly 1040. However, it is to be understood that theforce measurement assembly 1040 can be operatively coupled to the dataacquisition/data processing device 1040 using other signal transmissionmeans, such as a wireless data transmission system. If a wireless datatransmission system is employed, it is preferable to provide the forcemeasurement assembly 1040 with a separate power supply in the form of aninternal power supply or a dedicated external power supply.

Referring again to FIG. 34, it can be seen that the force measurementassembly 1040 of the illustrated embodiment is in the form of a forceplate assembly with a single, continuous measurement surface. The forceplate assembly includes a plate component 1042 supported on a pluralityof load transducers 1000, 1000′. As shown in FIGS. 34 and 35, the platecomponent 1042 comprises a top measurement surface 1044, a bottomsurface 1054 disposed generally opposite to the top measurement surface1044, and a plurality of side surfaces 1046, 1048, 1050, 1052 disposedbetween the top and bottom surfaces 1044, 1054. In the illustratedembodiment, the first side surface 1046 of the plate component 1042 isdisposed generally parallel to the second side surface 1048, and isdisposed generally perpendicular to both the third side surface 1050 andthe fourth side surface 1052. The third side surface 1050 of the platecomponent 1042 is disposed generally parallel to the fourth side surface1052, and is disposed generally perpendicular to both the first sidesurface 1046 and the second side surface 1048. Turning to the explodedview of FIG. 36, it can be seen that the bottom surface 1054 of theplate component 1042 comprises a plurality of transducer mountingrecesses 1056 for accommodating respective ones of the load transducers1000, 1000′. Also, as shown in FIG. 36, it can be seen that an L-shapedtransducer standoff plate 1034 is provided in each of the transducermounting recesses 1056 for spacing the top surfaces of the loadtransducers 1000, 1000′ from the mounting surfaces of the recesses 1056.Referring again to the bottom perspective view of FIG. 36, it can beseen that each L-shaped transducer standoff plate 1034 comprises aplurality of mounting apertures 1036 (e.g., three (3) apertures 1036)disposed therethrough for accommodating fasteners (e.g., screws) thatattach the plate component 1042 of the force measurement assembly 1040to either the load transducer 1000 or the load transducer 1000′. Assuch, the mounting apertures 1036 in each L-shaped transducer standoffplate 1034 are substantially aligned with the mounting apertures 1020 inthe load transducers 1000, 1000′ such that they correspond thereto. Inaddition, with reference again to FIG. 36, it can be seen that eachL-shaped transducer standoff plate 1034 further comprises pin locatingapertures 1038 (e.g., two (2) apertures 1038) formed therein forreceiving locating pins that ensure the proper positioning of the loadtransducers 1000, 1000′ on the plate component 1042 of the forcemeasurement assembly 1040. Thus, the pin locating apertures 1038 in eachL-shaped transducer standoff plate 1034 are substantially aligned withthe pin locating bores 1022 in the load transducers 1000, 1000′ suchthat they correspond thereto. The pin locating apertures 1038 in theL-shaped transducer standoff plates 1034, and the pin locating bores1022 in the load transducers 1000, 1000′, collectively receive locatingpins that ensure the proper positioning of the load transducers 1000,1000′ on the plate component 1042 of the force measurement assembly1040.

In illustrated embodiment of FIGS. 34-36, the force measurement assembly1040 comprises a total of four (4) load transducers 1000, 1000′ that aredisposed underneath, and near each of the respective four corners (4) ofthe plate component 1042. The load transducers 1000′ are generally thesame as the load transducers 1000, expect that they are configured as amirror image of the load transducers 1000. Advantageously, because theload transducers 1000, 1000′ are compact, none of the plurality of loadtransducers 1000, 1000′ extend substantially an entire length or widthof the plate component 1042 of the force measurement assembly 1040. Thecompact construction of the load transducers 1000, 1000′ not onlyreduces material costs because less material is used to form the loadtransducers 1000, 1000′, but it also allows the load transducers 1000,1000′ to be universally used on force plates having a myriad ofdifferent lengths and widths because it is not necessary for the loadtransducers 1000, 1000′ to conform to the footprint size of the forceplate.

In an alternative embodiment, rather than using the load transducers1000, 1000′ on the force measurement assembly 1040, the load transducers900 described above could be provided on the force measurement assembly1040. Using the load transducers 900 in lieu of the load transducers1000, 1000′ would enable the moment components of the load applied tothe plate component 1042 to be measured in addition to the forcecomponents of the load.

In other embodiments of the invention, rather than using a forcemeasurement assembly 1040 having a plate component 1042 with a singlemeasurement surface 1044, it is to be understood that a forcemeasurement assembly in the form of a dual force plate may bealternatively employed. Unlike the single force plate assembly 1040illustrated in FIGS. 34-36, the dual force plate comprises two separateplate components, each of which is configured to accommodate arespective one of a subject's feet thereon (i.e., the left platecomponent accommodates the subject's left foot, whereas the right platecomponent accommodates the subject's right foot). In these alternativeembodiments, each of the two plate components of the dual force plateare supported on four (4) load transducers 1000, 1000′ (i.e., a loadtransducer 1000, 1000′ is disposed in each of the respective four (4)corners of each of the two plate components). As such, the dual forceplate comprises a total of eight (8) load transducers 1000, 1000′ (i.e.,four (4) load transducers 1000, 1000′ under each of the two platecomponents).

Also, as shown in FIGS. 34-36, the force measurement assembly 1040 isprovided with a plurality of support feet 1058 disposed thereunder.Preferably, each of the four (4) corners of the force measurementassembly 1040 is provided with a support foot 1058 (e.g., mounted on thebottom of each load transducer 1000, 1000′). In particular, in theillustrated embodiment, each support foot 1058 is attached to anaperture 1024 in a respective one of the load transducers 1000, 1000′ bymeans of a fastener (e.g., a screw). In one embodiment, at least one ofthe support feet 1058 is adjustable so as to facilitate the leveling ofthe force measurement assembly 1040 on an uneven floor surface.

Now, turning to FIG. 37, it can be seen that the data acquisition/dataprocessing device 1060 (i.e., the laptop computing device) of the forcemeasurement system comprises a microprocessor 1060 a for processingdata, memory 1060 b (e.g., random access memory or RAM) for storing dataduring the processing thereof, and data storage device(s) 1060 c, suchas one or more hard drives, compact disk drives, floppy disk drives,flash drives, or any combination thereof. As shown in FIG. 37, the forcemeasurement assembly 1040 and the visual display device 1070 areoperatively coupled to the core components 1060 a, 1060 b, 1060 c of thedata acquisition/data processing device 1060 such that data is capableof being transferred between these devices 1040, 1060 a, 1060 b, 1060 c,and 1070. Also, as illustrated in FIG. 37, a plurality of data inputdevices 1066, 1068 such as the keyboard 1066 and mouse 1068 shown inFIG. 34, are operatively coupled to the core components 1060 a, 1060 b,1060 c of the data acquisition/data processing device 1060 so that auser is able to enter data into the data acquisition/data processingdevice 1060. In some embodiments, the data acquisition/data processingdevice 1060 can be in the form of a laptop computer, while in otherembodiments, the data acquisition/data processing device 1060 can beembodied as a desktop computer.

FIG. 38 graphically illustrates the acquisition and processing of theload data carried out by the exemplary force measurement system of FIG.34. Initially, as shown in FIG. 38, a load L is applied to the forcemeasurement assembly 1040 (e.g., by a subject disposed thereon). Theload is transmitted from the plate component 1042 to the loadtransducers 1000, 1000′ disposed in each of its four (4) corners. Asdescribed above, in the illustrated embodiment, each of the loadtransducers 1000, 1000′ includes a plurality of strain gages 1026, 1028,1030 wired in one or more Wheatstone bridge configurations, wherein theelectrical resistance of each strain gage is altered when the associatedbeam portion of the load transducer 1000, 1000′ undergoes deformationresulting from the load (i.e., forces and/or moments) acting on theplate component 1042. For each plurality of strain gages disposed on theload transducers 1000, 1000′, the change in the electrical resistance ofthe strain gages brings about a consequential change in the outputvoltage of the Wheatstone bridge (i.e., a quantity representative of theload being applied to the measurement surface 1044). Thus, in oneembodiment, the four (4) load transducers 1000, 1000′ disposed under theplate component 1042 output a total of twelve (12) analog outputvoltages (signals). In some embodiments, the twelve (12) analog outputvoltages from load transducers 1000, 1000′ disposed under the platecomponent 1042 are then transmitted to a preamplifier board (not shown)for preconditioning. The preamplifier board is used to increase themagnitudes of the transducer analog voltages, and preferably, to convertthe analog voltage signals into digital voltage signals as well. Afterwhich, the force measurement assembly 1040 transmits the force plateoutput signals S_(FPO1)-S_(FP12) to a main signal amplifier/converter1072. Depending on whether the preamplifier board also includes ananalog-to-digital (A/D) converter, the force plate output signalsS_(FPO1)-S_(FP12) could be either in the form of analog signals ordigital signals. The main signal amplifier/converter 1072 furthermagnifies the force plate output signals S_(FPO1)-S_(FP12,) and if thesignals S_(FPO1)-S_(FP12) are of the analog-type (for a case where thepreamplifier board did not include an analog-to-digital (A/D)converter), it may also convert the analog signals to digital signals.Then, the signal amplifier/converter 1072 transmits either the digitalor analog signals S_(ACO1)-S_(AC12) to the data acquisition/dataprocessing device 1060 (computer 1060) so that the forces and/or momentsthat are being applied to the measurement surface 1044 of the forcemeasurement assembly 1040 can be transformed into output load values OL.In addition to the components 1060 a, 1060 b, 1060 c, the dataacquisition/data processing device 1060 may further comprise ananalog-to-digital (A/D) converter if the signals S_(ACO1)-S_(AC12) arein the form of analog signals. In such a case, the analog-to-digitalconverter will convert the analog signals into digital signals forprocessing by the microprocessor 1060 a.

When the data acquisition/data processing device 1060 receives thevoltage signals S_(ACO1)-S_(AC12), it initially transforms the signalsinto output forces by multiplying the voltage signals S_(ACO1)-S_(AC12)by a calibration matrix. If the load transducer 900 is used inconjunction with the force measurement assembly 1040, the dataacquisition/data processing device 1060 may additionally transform thesignals into output moments by multiplying the voltage signals by thecalibration matrix. After which, the force exerted on the surface 1044of the force measurement assembly 1040, and the center of pressure ofthe applied force (i.e., the x and y coordinates of the point ofapplication of the force applied to the measurement surface 1044) isdetermined by the data acquisition/data processing device 1060.Referring to the perspective view of FIG. 34, it can be seen that thecenter of pressure coordinates (x_(P) _(L) , y_(P) _(L) ) for the platecomponent 1042 of the force measurement assembly 1040 are determined inaccordance with x and y coordinate axes 1074, 1076.

In one exemplary embodiment, the data acquisition/data processing device1060 determines all three (3) orthogonal components of the resultantforces acting on the plate component 1042 of the force measurementassembly 1040 (i.e., F_(X), F_(Y), F_(Z)). In yet other embodiments ofthe invention, all three (3) orthogonal components of the resultantforces and moments acting on the plate component 1042 of the forcemeasurement assembly 1040 (i.e., F_(X), F_(Y), F_(Z), M_(X), M_(Y),M_(Z),) may be determined (i.e., when the load transducer 900 is used inlieu of the load transducers 1000, 1000′).

Any of the features or attributes of the above described embodiments andvariations can be used in combination with any of the other features andattributes of the above described embodiments and variations as desired.

It is apparent from the above detailed description that the presentinvention provides a low profile six-component load transducer 10, 10′,100, 200, 300, 400, 500, 600, 700, 800 which has a significant allowableoffset for the line of action of the force. In that, for a givenallowable maximum load, this load transducer has a much higher momentcapacity than currently available load transducers and the offset valuecan be as high as five times the diameter (or width dimension) of thetransducer. Therefore, the load transducer 10, 10′, 100, 200, 300, 400,500, 600, 700, 800 according to the present invention is able towithstand and measure moments which are approximately ten times higherthan that of a similarly sized and rated conventional load cell.

Also, it is readily apparent that the embodiments of the load transducer900, 1000, 1000′ and the force measurement assembly 1040 using the sameoffer numerous advantages and benefits. In particular, the loadtransducer 900, 1000, 1000′ described herein is capable of beinginterchangeably used with a myriad of different force plate sizes sothat load transducers that are specifically tailored for a particularforce plate size are unnecessary. Moreover, the universal loadtransducer 900, 1000, 1000′ described herein is compact and uses lessstock material than conventional load transducers, thereby resulting inlower material costs. Furthermore, the aforedescribed force measurementassembly 1040 utilizes the compact and universal load transducer 900,1000, 1000′ thereon so as to result in a more lightweight and portableforce measurement assembly.

From the foregoing disclosure and detailed description of certainpreferred embodiments, it is also apparent that various modifications,additions and other alternative embodiments are possible withoutdeparting from the true scope and spirit of the present invention. Theembodiments discussed were chosen and described to provide the bestillustration of the principles of the present invention and itspractical application to thereby enable one of ordinary skill in the artto utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the presentinvention as determined by the appended claims when interpreted inaccordance with the benefit to which they are fairly, legally, andequitably entitled.

The invention claimed is:
 1. A load transducer comprising, incombination: a plurality of beam portions connected to one another insuccession, the plurality of beam portions being arranged in acircumscribing pattern whereby a central one of the plurality of beamportions is at least partially circumscribed by one or more outer onesof the plurality of beam portions, a first one of the plurality of beamportions having a first surface and a second one of the plurality ofbeam portions having a second surface, the first surface being disposedat an angle relative to the second surface; and at least one load celldisposed on one or more of the plurality of beam portions, the at leastone load cell configured to measure at least one force or momentcomponent of a load applied to the load transducer, the at least oneload cell including a first deformation sensing element disposed on thefirst surface and a second deformation sensing element disposed on thesecond surface.
 2. The load transducer according to claim 1, wherein atleast one of the first and second deformation sensing elements of the atleast one load cell comprises a strain gage configured to measure the atleast one force or moment component of the load applied to the loadtransducer.
 3. The load transducer according to claim 1, wherein theplurality of beam portions are each part of a transducer frame, thetransducer frame being compact and of one-piece construction.
 4. Theload transducer according to claim 1, wherein the circumscribing patternin which the plurality of beam portions are arranged is generallyG-shaped.
 5. The load transducer according to claim 1, wherein thecircumscribing pattern in which the plurality of beam portions arearranged is generally spiral-shaped.
 6. The load transducer according toclaim 1, wherein the at least one load cell comprises at least threeload cells, each of the at least three load cells being disposed on arespective one of the plurality of beam portions, a first of the atleast three load cells configured to be sensitive to a vertical forcecomponent, a second of the at least three load cells configured to besensitive to a first shear force component, a third of the at leastthree load cells configured to be sensitive to a second shear forcecomponent, the first shear force component being generally perpendicularto the second shear force component, and each of the first and secondshear force components being generally perpendicular to the verticalforce component.
 7. The load transducer according to claim 1, whereinthe plurality of beam portions comprises at least two pairs of beamportions that are disposed generally parallel to one another.
 8. Theload transducer according to claim 7, wherein each of the at least twopairs of beam portions comprises two beam portions that are laterallyspaced apart from one another by a gap.
 9. The load transducer accordingto claim 1, wherein one or more of the plurality of beam portionscomprises a first top surface that is disposed at a first elevationrelative to a bottom surface of the load transducer and a second topsurface that is disposed at a second elevation relative to the bottomsurface of the load transducer, the second elevation being greater thanthe first elevation; and wherein a recessed area created by thedifference in elevation between the second elevation and the firstelevation is used to accommodate one or more electrical components ofthe at least one load cell.
 10. A load transducer comprising, incombination: a plurality of beam portions connected to one another insuccession, the plurality of beam portions being arranged in a at leasta partially looped configuration or an L-shaped configuration, a firstone of the plurality of beam portions having a first surface and asecond one of the plurality of beam portions having a second surface,the first surface being disposed at an angle relative to the secondsurface; and a plurality of load cells, each of the load cells beingdisposed on a respective one of the plurality of beam portions, theplurality of load cells configured to measure one or more forcecomponents or one or more moment components, or both one or more forcecomponents and one or more moment components, the plurality of loadcells including a first deformation sensing element disposed on thefirst surface and a second deformation sensing element disposed on thesecond surface.
 11. The load transducer according to claim 10, whereinthe plurality of beam portions are arranged in a looped configuration,and wherein the looped configuration in which the plurality of beamportions are arranged is generally C shaped.
 12. The load transduceraccording to claim 10, wherein the plurality of beam portions arearranged in a looped configuration, and wherein the looped configurationin which the plurality of beam portions are arranged is generallyspiral-shaped.
 13. The load transducer according to claim 10, whereinthe plurality of load cells comprises at least three load cells, each ofthe at least three load cells being disposed on a respective one of theplurality of beam portions, a first of the at least three load cellsconfigured to be sensitive to a vertical force component, a second ofthe at least three load cells configured to be sensitive to a firstshear force component, a third of the at least three load cellsconfigured to be sensitive to a second shear force component, the firstshear force component being generally perpendicular to the second shearforce component, and each of the first and second shear force componentsbeing generally perpendicular to the vertical force component.
 14. Theload transducer according to claim 10, wherein one or more of theplurality of beam portions comprises a mounting aperture disposed near arespective end thereof for accommodating a fastener.
 15. The loadtransducer according to claim 10, wherein one or more of the pluralityof beam portions comprises an aperture disposed therein and wherein atleast one of the first and second deformation sensing elements comprisesa strain gage disposed on an outer surface of the one or more of theplurality of beam portions, the outer surface of the one or more of theplurality of beam portions on which the strain gage is disposed beinggenerally opposite to an inner surface of the aperture.
 16. The loadtransducer according to claim 10, wherein one or more of the pluralityof beam portions comprises a first top surface that is disposed at afirst elevation relative to a bottom surface of the load transducer anda second top surface that is disposed at a second elevation relative tothe bottom surface of the load transducer, the second elevation beinggreater than the first elevation; and wherein a recessed area created bythe difference in elevation between the second elevation and the firstelevation is used to accommodate one or more electrical components ofthe at least one load cell.
 17. A force measurement assembly comprising,in combination: at least one plate component having a measurementsurface for receiving a portion of a body of a subject; and a pluralityof load transducers, each of the plurality of load transducersincluding: a plurality of beam portions connected to one another insuccession, the plurality of beam portions being arranged in acircumscribing pattern whereby a central one of the plurality of beamportions is at least partially circumscribed by one or more outer onesof the plurality of beam portions; and at least one load cell disposedon one of the plurality of beam portions, the at least one load cellconfigured to measure at least one force or moment component of a loadapplied to the load transducer; wherein one or more of the plurality ofload transducers is disposed proximate to a respective corner of the atleast one plate component; and wherein at least one of the plurality ofload transducers comprises a first top surface that is disposed at afirst elevation relative to a bottom surface of the load transducer anda second top surface that is disposed at a second elevation relative tothe bottom surface of the load transducer, the second elevation beinggreater than the first elevation; and wherein a recessed area created bythe difference in elevation between the second elevation and the firstelevation is used to accommodate one or more electrical components ofthe at least one load cell of the load transducer.
 18. The forcemeasurement assembly according to claim 17, wherein none of theplurality of load transducers extend substantially an entire length orwidth of the at least one plate component.
 19. (canceled)
 20. The loadtransducer according to claim 1, wherein the plurality of beam portionsconnected to one another in succession comprises two or more beamportions connected to one another in succession.
 21. The load transduceraccording to claim 10, wherein each of the plurality of beam portionsconnected to one another in succession are connected to one another inan end-to-end configuration.
 22. The load transducer according to claim10, wherein the plurality of beam portions are arranged in a loopedconfiguration, and wherein, in the looped configuration, a central oneof the plurality of beam portions emanates from a generally centrallocation within a footprint of the load transducer and outer ones of theplurality of beam portions are wrapped around the central one of theplurality of beam portions.